1 February 2007A giant cloud half the size of the United States has been imaged on Saturn’s moon Titan by the Cassini spacecraft. The cloud may be responsible for the material that fills the lakes discovered last year by Cassini's radar instrument.

Cloaked by winter's shadow, this cloud has now come into view as winter turns to spring. The cloud extends down to 60 degrees north latitude, is roughly 2400 kilometers in diameter and engulfs almost the entire north pole of Titan.

The new image was acquired on 29 December 2006, by Cassini's visual and infrared mapping spectrometer (VIMS). Scientific models predicted this cloud system but it had never been imaged with such details before.

"We knew this cloud had to be there but were amazed at its size and structure," said Dr. Christophe Sotin of the University of Nantes, France, a member of the visual and infrared mapping spectrometer team and distinguished visiting scientist at NASA's Jet Propulsion Laboratory, Pasadena, California. "This cloud system may be a key element in the global formation of organics and their interaction with the surface."

The same cloud system seen on 29 December 2006, was still there two weeks later during the flyby which took place on 13 January 2007, even though observing conditions were slightly less favorable than in December.

The Cassini radar team reported last year that the lakes at the north pole are partly filled and some appear to have evaporated, likely contributing to this cloud formation, which is made up of ethane, methane and other organics.

These findings reinforce the idea that methane rains down onto the surface to form lakes, and then evaporates to form clouds. Scientists compare this methane cycle to the hydrological cycle on Earth, dubbing it 'methane-ologic cycle'.

Ground-based observations show this Titan cloud system comes and goes with the seasons. A season on Titan lasts approximately seven Earth years. Based on the global circulation models, it seems that such cloud activity can last about 25 Earth years before almost vanishing for four to five years, and then appearing again for 25 years.

Scientists expect this cloud to be around for several years. As the seasons change, scientists expect a shift of these clouds and lakes from the north pole to the south pole. On Titan's south pole, scientists have seen only one kidney-shaped lake with Cassini’s imaging cameras.

"With 16 more flybys to come this year, we should have the opportunity to monitor the evolution of this cloud system over time," said Dr. Stephane Le Mouelic, working with the Cassini visual and infrared mapping spectrometer team, and also at the University of Nantes.

13-Feb-2007: A brand new image taken with Hubble’s Wide Field Planetary Camera 2 shows the planetary nebula NGC 2440 - the chaotic structure of the demise of a star.

This image, just taken by the NASA/ESA Hubble Space Telescope, shows the colourful “last hurrah” of a star like our Sun. The star is ending its life by casting off its outer layers of gas, which formed a cocoon around the star’s remaining core. Ultraviolet light from the dying star makes the material glow. The burned-out star, called a white dwarf, is the white dot in the centre. Our Sun will eventually burn out and shroud itself with stellar debris, but not for another 5 billion years.

Our Milky Way Galaxy is littered with these stellar relics, called planetary nebulae. The objects have nothing to do with planets. Eighteenth- and nineteenth-century astronomers called them the name because through small telescopes they resembled the disks of the distant planets Uranus and Neptune. The planetary nebula in this image is called NGC 2440. The white dwarf at the centre of NGC 2440 is one of the hottest known, with a surface temperature of more than 200,000 degrees Celsius. The nebula’s chaotic structure suggests that the star shed its mass episodically. During each outburst, the star expelled material in a different direction. This can be seen in the two bowtie-shaped lobes. The nebula also is rich in clouds of dust, some of which form long, dark streaks pointing away from the star. NGC 2440 lies about 4,000 light-years from Earth in the direction of the constellation Puppis.

The material expelled by the star glows with different colours depending on its composition, its density and how close it is to the hot central star. Blue samples helium; blue-green oxygen, and red nitrogen and hydrogen. The image was taken 6 February, 2007 with Hubble’s Wide Field Planetary Camera 2.

NASA's Hubble Space Telescope, in collaboration with several other ground- and space- based telescopes, has captured a galaxy being ripped apart by a galaxy cluster's gravitational field and harsh environment.

The finding sheds light on the mysterious process by which gas-rich spiral-shaped galaxies might evolve into gas-poor irregular- or elliptical-shaped galaxies over billions of years. The new observations also reveal one mechanism for forming the millions of "homeless" stars seen scattered throughout galaxy clusters.

Twenty years ago, astronomers witnessed one of the brightest stellar explosions in more than 400 years. The titanic supernova, called SN 1987A, blazed with the power of 100 million suns for several months following its discovery on Feb. 23, 1987. Observations of SN 1987A, made over the past 20 years by NASA’s Hubble Space Telescope and many other major ground- and space-based telescopes, have significantly changed astronomers' views of how massive stars end their lives. Astronomers credit Hubble's sharp vision with yielding important clues about the massive star's demise.

This Hubble telescope image shows the supernova’s triple-ring system, including the bright spots along the inner ring of gas surrounding the exploded star. A shock wave of material unleashed by the stellar blast is slamming into regions along the inner ring, heating them up, and causing them to glow. The ring, about a light-year across, was probably shed by the star about 20,000 years before it exploded.

This NASA Hubble Space Telescope image shows the diverse collection of galaxies in a galaxy cluster called Abell S0740, located more than 450 million light-years away in the constellation Centaurus. The giant elliptical galaxy ESO 325-G004 looms large at the cluster's center. This galaxy is as massive as 100 billion suns. Hubble resolves thousands of globular star clusters orbiting ESO 325-G004. Globular clusters are compact groups of hundreds of thousands of stars that are gravitationally bound together. At the galaxy's distance they appear as pinpoints of light contained within the diffuse halo. Other elliptical and spiral galaxies appear in the image. The photo was made from images taken using Hubble's Advanced Camera for Surveys in January 2005 and February 2006.

New images and data from the European Space Agency's mission to Venus provide new insights into the turbulent and noxious atmosphere of Earth's sister planet. What causes violent winds and turbulences? Is the surface topography playing a role in the complex global dynamics of the atmosphere? Venus Express is on the case.

Four different views of the Venusian cloud system are seen here from Venus Express. The grey-scale of the images is such that black means more transparency, therefore less clouds, while white means more opacity, therefore more cloud concentration. Credits: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA

Venus' atmosphere represents a true puzzle for scientists. Winds are so powerful and fast that they circumnavigate the planet in only four Earth days - the atmospheric 'super-rotation' - while the planet itself is very slow in comparison, taking 243 Earth days to perform one full rotation around its axis.

At the poles things get really complicated with huge double-eyed vortices providing a truly dramatic view. In addition, a layer of dense clouds covers the whole planet as a thick curtain, preventing observers using conventional optical means from seeing what lies beneath.

Venus Express is on the contrary capable of looking through the atmosphere at different depths, by probing it at different infrared wavelengths. The Ultraviolet, Visible and Near-Infrared Mapping Spectrometer (VIRTIS) on board is continuing its systematic investigation of Venus' atmospheric layers to solve the riddle of the causes for such turbulent and stormy atmosphere.

The images presented with this article focus on Venusian atmospheric turbulences and cloud features, whose shape and size vary with planetary latitudes. At the equator, clouds are irregular and assume a peculiar 'bubble'-shape. At mid latitudes they are more regular and streaky, running almost parallel to the direction of the super rotation with speed reaching more than 400 kilometres per hour. Going higher up in latitude, in the polar region, the clouds end up in entering a vortex shape.

The NASA/ESA Hubble Space Telescope has delivered an unrivalled snapshot of the nearby barred spiral galaxy NGC 1672. This remarkable image provides a high definition view of the galaxy's large bar, its fields of star-forming clouds and dark bands of interstellar dust.

NGC 1672, visible from the Southern Hemisphere, is seen almost face on and shows regions of intense star formation. The greatest concentrations of star formation are found in the so-called starburst regions near the ends of the galaxy's strong galactic bar. NGC 1672 is a prototypical barred spiral galaxy and differs from normal spiral galaxies in that the spiral arms do not twist all the way into the centre. Instead, they are attached to the two ends of a straight bar of stars enclosing the nucleus.

Astronomers believe that barred spirals have a unique mechanism that channels gas from the disk inwards towards the nucleus. This allows the bar portion of the galaxy to serve as an area of new star generation. It appears that the bars are short-lived, begging the question: will non-barred galaxies develop a bar in the future, or have they already hosted one that has disappeared?

In the new image from the NASA/ESA Hubble Space Telescope, clusters of hot young blue stars form along the spiral arms, and ionize surrounding clouds of hydrogen gas that glow red. Delicate curtains of dust partially obscure and redden the light of the stars behind them. NGC 1672's symmetric look is emphasised by the four principal arms, edged by eye-catching dust lanes that extend out from the centre.

Galaxies lying behind NGC 1672 give the illusion they are embedded in the foreground galaxy, even though they are really much farther away. They also appear reddened as they shine through NGC 1672's dust. A few bright foreground stars inside our own Milky Way Galaxy appear in the image as bright, diamond-like objects.

NGC 1672 is a member of the family of Seyfert galaxies, named after the astronomer, Carl Keenan Seyfert, who studied a family of galaxies with active nuclei extensively in the 1940s. The energy output of these nuclei can sometimes outshine their host galaxies. The active galaxy family include the exotically named quasars and blazars. Although each type has distinctive characteristics, they are thought to be all driven by the same engine - supermassive black holes - but are viewed from different angles.

The new Hubble observations, performed with the Advanced Camera for Surveys aboard the observatory, have shed light on the process of starburst activity and on why some galaxies are ablaze with extremely active star formation.

NGC 1672 is more than 60 million light-years away in the direction of the Southern constellation of Dorado. These observations of NGC 1672 were taken with Hubble's Advanced Camera for Surveys in August of 2005. This composite image contains filters that isolate light from the blue, green, and infrared portions of the spectrum, as well as emission from ionized hydrogen.

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

For the first time ever, NASA researchers have successfully demonstrated in the laboratory that a space telescope rigged with special masks and mirrors could snap a photo of an Earth-like planet orbiting a nearby star. This accomplishment marks a dramatic step forward for missions like the proposed Terrestrial Planet Finder, designed to hunt for an Earth twin that might harbor life.

Three simulated planets -- one as bright as Jupiter, one half as bright as Jupiter and one as faint as Earth -- stand out plainly in this image created from a sequence of 480 images captured by the High Contrast Imaging Testbed at JPL. The asterisk marks the location of the system's simulated star. Credit: NASA/JPL-Caltech

Trying to image an exoplanet - a planet orbiting a star other than the sun - is a daunting task, because its relatively dim glow is easily overpowered by the intense glare of its much bigger, brighter parent star. The challenge has been compared to looking for a firefly next to a searchlight.

Now, two researchers at NASA's Jet Propulsion Laboratory in Pasadena, Calif., have shown that a fairly simple coronagraph - an instrument used to "mask" a star's glare - paired with an adjustable mirror, could enable a space telescope to image a distant planet 10 billion times fainter than its central star.

"Our experiment demonstrates the suppression of glare extremely close to a star, clearing a field dark enough to allow us to see an Earth twin. This is at least a thousand times better than anything demonstrated previously," said John Trauger, lead author of a paper appearing in the April 12 issue of Nature. This paper describes the system, called the High Contrast Imaging Testbed, and how the technique could be used with a telescope in space to see exoplanets. The lab experiment used a laser as a simulated star, with fainter copies of the star serving as "planets."

To date, scientists have used various techniques to detect more than 200 exoplanets. Most of these exoplanets are from five to 4,000 times more massive than Earth, and are either too hot, too cold or too much of a giant gas ball to be considered likely habitats for life. So far, no one has managed to capture an image of an exoplanetary system that resembles our own solar system. Scientists are eager to take a closer look at nearby systems, to hunt for and then characterize any Earth-like planets - those with the right size, orbit and other traits considered friendly for life.

In the lab demonstration, the High Contrast and Imaging Testbed overcame two significant hurdles that all telescopes face when trying to image exoplanets - diffracted and scattered light.

When starlight hits the edge of a telescope's primary mirror, it becomes slightly disturbed, producing a pattern of rings or spikes surrounding the major source of light in the focused image. This diffracted light can completely obscure any planets in the field of view.

To address this problem, Trauger and his colleagues at JPL fashioned a pair of masks for their system. The first, which resembles a blurry barcode, directly blocks most of the starlight, while the second clears away the diffracted rings and spikes. The combination creates enough darkness to allow the light of any planets to shine through.

"Mathematically, and sort of magically, this coronagraph blocks both the central star and its rings," said Wesley Traub of JPL, co-author of the new paper and Terrestrial Planet Finder project scientist.

Scattered light presents the additional hurdle. Minor ripples on a telescope's mirror produce "speckles" - faint copies of a star, shifted to the side, which can also hide planets. In the High Contrast Imaging Testbed, a deformable mirror the size of a large coin limits scattered light. With a surface that can be altered ever so slightly by computer-controlled actuators, this mirror compensates for the effects of minor imperfections in the telescope and instrument.

"This result is important because it points the way to building a space telescope with the ability to detect and characterize Earth-like planets around nearby stars," Traub said.

For their next steps, Trauger and Traub plan to improve the suppression of speckles by a factor of 10, and extend the method to accommodate many wavelengths of light simultaneously.

JPL manages the Terrestrial Planet Finder mission for NASA's Science Mission Directorate, Washington. JPL is a division of the California Institute of Technology in Pasadena.

Using a quartet of space observatories, University of Maryland astronomers may have cracked a 45-year mystery surrounding two ghostly spiral arms in the galaxy M106.

The Maryland team, led by Yuxuan Yang, took advantage of the unique capabilities of NASA's Chandra X-ray Observatory, NASA's Spitzer Space Telescope, the European Space Agency's XMM-Newton X-ray observatory, and data obtained almost a decade ago with NASA's Hubble Space Telescope.

In this composite image of spiral galaxy M106 (NGC 4258), radio data from the Very Large Array appears as blue, X-ray data from Chandra is coded red, and infrared data from the Spitzer Space Telescope appears green. The anomalous arms appear as purple and blue emission. Credit: X-ray: NASA/CXC/Univ. of Maryland/A.S. Wilson et al. IR: NASA/JPL-Caltech; VLA & NRAO/AUI/NSF

M106 (also known as NGC 4258) is a stately spiral galaxy 23.5 million light-years away in the constellation Canes Venatici. In visible-light images, two prominent arms emanate from the bright nucleus and spiral outward. These arms are dominated by young, bright stars, which light up the gas within the arms. "But in radio and X-ray images, two additional spiral arms dominate the picture, appearing as ghostly apparitions between the main arms," says team member Andrew Wilson of the University of Maryland. These so-called "anomalous arms" consist mostly of gas.

"The nature of these anomalous arms is a long-standing puzzle in astronomy," says Yang. "They have been a mystery since they were first discovered in the early 1960s."

By analyzing data from XMM-Newton, Spitzer, and Chandra, Yang, Bo Li, Wilson, and Christopher Reynolds, all at the University of Maryland at College Park, have confirmed earlier suspicions that the ghostly arms represent regions of gas that are being violently heated by shock waves.

Previously, some astronomers had suggested that the anomalous arms are jets of particles being ejected by a supermassive black hole in M106's nucleus. But radio observations by the National Radio Astronomy Observatory's Very Long Baseline Array, and the Very Large Array in New Mexico, later identified another pair of jets originating in the core. "It is highly unlikely that an active galactic nucleus could have more than one pair of jets," says Yang.

In 2001, Wilson, Yang, and Gerald Cecil, of the University of North Carolina, Chapel Hill, noted that the two jets are tipped 30 degrees with respect to the galaxy disk. But if one could vertically project the jets onto the disk, they would line up almost perfectly with the anomalous arms. Figuring that this alignment was not strictly a matter of chance, Wilson, Yang, and Cecil proposed that the jets heat the gas in their line of travel, forming an expanding cocoon. Because the jets lie close to M106's disk, the cocoon heats gas in the disk and generates shock waves, heating the gas to millions of degrees and causing it to radiate brightly in X-rays and other wavelengths.

To test this idea, Yang and his colleagues looked at archival spectral observations from XMM-Newton. With XMM-Newton's superb sensitivity, the team could measure the gas temperature in the anomalous arms and also see how strongly X-rays from the gas are absorbed en route by intervening material.

"One of the predictions of this scenario is that the anomalous arms will gradually be pushed out of the galactic disk plane by jet-heated gas," says Yang. The XMM-Newton spectra show that X-rays are more strongly absorbed in the direction of the northwest arm than in the southeast arm. The results strongly suggest that the southeast arm is partly on the near side of M106's disk, and the northwest arm is partly on the far side.

The scientists noted that these observations show clear consistency with their scenario. Confirmation of this interpretation has recently come from archival observations from NASA's Spitzer Space Telescope, whose infrared view shows clear signs that X-ray emission from the northwest arm is being absorbed by warm gas and dust in the galaxy's disk. Moreover, Chandra's superior imaging resolution gives clear indications of gas shocked by interactions with the two jets.

Besides addressing the mystery of the anomalous arms, these observations allowed the team to estimate the energy in the jets and gauge their relationship to M106's central black hole. The team's paper will appear in the May 10 issue of the Astrophysical Journal.

MWC 922: The Red Square NebulaExplanation: What could cause a nebula to appear square? No one is quite sure. The hot star system known as MWC 922, however, appears to be imbedded in a nebula with just such a shape. The above image combines infrared exposures from the Hale Telescope on Mt. Palomar in California, and the Keck-2 Telescope on Mauna Kea in Hawaii. A leading progenitor hypothesis for the square nebula is that the central star or stars somehow expelled cones of gas during a late developmental stage. For MWC 922, these cones happen to incorporate nearly right angles and be visible from the sides. Supporting evidence for the cone hypothesis includes radial spokes in the image that might run along the cone walls. Researchers speculate that the cones viewed from another angle would appear similar to the gigantic rings of supernova 1987A, possibly indicating that a star in MWC 922 might one day itself explode in a similar supernova

Logged

They say that when you die, your life flashes in front of you. Make it worth watching!

PASADENA, Calif. - Astronomers have laid down the cosmic equivalent of yellow "caution" tape around super hot stars, marking the zones where cooler stars are in danger of having their developing planets blasted away.

This infrared image from Spitzer shows the Rosette nebula, a pretty star-forming region more than 5,000 light-years away in the constellation Monoceros. In optical light, the nebula looks like a rosebud, or the "rosette" adornments that date back to antiquity. Credit: NASA/JPL-Caltech/Z. Balog (Univ. of Ariz./Univ. of Szeged)

In a new study from NASA's Spitzer Space Telescope, scientists report the first maps of so-called planetary "danger zones." These are areas where winds and radiation from super hot stars can strip other young, cooler stars like our sun of their planet-forming materials. The results show that cooler stars are safe as long as they lie beyond about 1.6 light-years, or nearly 10 trillion miles, of any hot stars. But cooler stars inside the zone are likely to see their potential planets boiled off into space.

"Stars move around all the time, so if one wanders into the danger zone and stays for too long, it will probably never be able to form planets," said Zoltan Balog of the University of Arizona, Tucson, lead author of the new report, appearing May 20 in the Astrophysical Journal.

The findings are helping astronomers pinpoint the types of environments where planets beyond our solar system, including some that might be hospitable to life, are most likely to form.

Planets are born out of a flat disk of gas and dust, called a protoplanetary disk, that swirls around a young star. They are believed to clump together out of the disk over millions of years, growing in size like dust bunnies as they sweep through the dust.

Previous studies revealed that these protoplanetary disks can be destroyed by the most massive, hottest type of star in the universe, called an O-star, over a period of about a million years. Ultraviolet radiation from an O-star heats and evaporates the dust and gas in the disk, then winds from the star blow the material away. Last year, Balog and his team used Spitzer to capture a stunning picture of this "photoevaporation" process at work.

The team's new study is the first systematic survey for disks in and around the danger zone, or "blast radius" of an O-star. They used Spitzer's heat-seeking infrared eyes to look for disks around 1,000 stars in the Rosette Nebula, a turbulent star-forming region 5,200 light-years away in the constellation Monoceros. The stars range between one-tenth and five times the mass of the sun and are between 2 and 3 million years old. They are all near at least one of the region's massive O-stars.

This artist's concept illustrates an O-star near the top right, just behind a young, cooler star and its swirling disk of planet-forming material. Credit: NASA/JPL-Caltech/T. Pyle (SSC)

The observations revealed that, beyond 10 trillion miles of an O-star, about 45 percent of the stars had disks - about the same amount as there were in safer neighborhoods free of O-stars. Within this distance, only 27 percent of the stars had disks, with fewer and fewer disks spotted around stars closest to the O-star. In other words, an O-star's danger zone is a sphere whose damaging effects are worst at the core. For reference, our sun's closest star, a small star called Proxima Centauri, is nearly 30 trillion miles away.

In addition, the new study indicates that a protoplanetary disk will boil off faster in the zone's perilous core. For example, a disk two times closer to an O-star than another disk will evaporate twice as fast. "The edges of the danger zone are sharply defined," said Balog. "It is relatively safe for protoplanetary disks outside it, whereas a disk that gets dragged along by its star to be really close to an O-star could disappear in as fast as a hundred thousand years."

Despite this doomsday scenario, there is a chance some planets could survive a close encounter with an O-star. According to one alternative theory of planet formation, some gas giants like Jupiter might form in less than one million years. If such a planet already existed around a young star whose disk is blown away, the gas giant would stay put while any burgeoning rocky planets like Earth would be forever swept away.

Some astronomers think our sun was born in a similarly violent neighborhood studded with O-stars before migrating to its present, more spacious home. If so, it was lucky enough to escape a harrowing ride into any danger zones, or our planets, and life as we know it, wouldn't be here today.

Blazing like an icy torch, the plume of Enceladus shines in scattered sunlight as the moon casts a shadow onto Saturn's E ring. Some of the tiny ice particles erupted from the moon's south polar region go into Saturn orbit, forming the doughnut-shaped ring, onto which the moon's shadow is cast in this view.

The shadow of Enceladus (505 kilometers, or 314 miles across) stretches away to the upper left at around the 10 o'clock position. The Sun-Enceladus-spacecraft, or phase, angle is 164 degrees here, with the Sun being located toward the lower right. This means that Enceladus' shadow extends toward the Cassini spacecraft -- through part of the E ring.

Some of the bright dots in this heavily processed view are background stars. Others are due to cosmic ray hits on the camera detector.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Aug. 11, 2006 at a distance of approximately 2.2 million kilometers (1.3 million miles) from Enceladus. Image scale is 13 kilometers (8 miles) per pixel.

Astronomers have found the lowest mass white dwarf known in our galaxy: a Saturn-sized ball of helium containing only about one-fifth the mass of the Sun. In addition, they have spotted the source of the white dwarf's radical weight-loss plan. An unseen companion, likely another white dwarf, has sucked away much of the tiny white dwarf's material, leaving it a shadow of its former self.

This artist's conception shows the lowest-mass white dwarf known in our galaxy and its companion star, which likely is another white dwarf. The foreground white dwarf underwent a radical weight-loss plan about 500 million years ago, losing mass to its companion. The low-mass white dwarf now weighs only about 17 percent as much as the Sun. Credit: David A. Aguilar (CfA)

"This star is bizarre," said Warren Brown of the Harvard-Smithsonian Center for Astrophysics. "It takes extraordinary circumstances to make such a low mass white dwarf."

When a Sun-like star ages and dies, it becomes a white dwarf. The newfound white dwarf, with the unwieldy designation of SDSS J091709.55+463821.8 (hereafter J0917+46) lies about 7,400 light-years from Earth near the border of the constellations Lynx and Ursa Major. Where a typical white dwarf holds about half a Sun's worth of material, the newfound white dwarf contains only a fraction of that mass.

"Our white dwarf is skinny in terms of mass, yet it looks fat in terms of its physical size," stated first author Mukremin Kilic of Ohio State University. "It's about nine times bigger than a typical white dwarf in diameter."

When the astronomers first found J0917+46, they predicted that it must have an unseen companion that had aided its weight loss. A subsequent radial velocity search, which looked for signs that the white dwarf wobbled when tugged by a companion's gravity, confirmed the prediction. The astronomers ruled out the possibility that the companion is either a low-mass main sequence star or a black hole. It must be either another white dwarf or a neutron star, with a white dwarf being the more likely candidate.

"No star is old enough to produce such an extremely low-mass white dwarf by itself," explained Brown. "Therefore, we knew that mass must have been stripped from the white dwarf by a companion."

"Finding the companion means that stellar evolution theories have passed a major test," added co-author Scott Kenyon of the Smithsonian Astrophysical Observatory. "The fact that the companion is a more massive white dwarf or neutron star is also consistent with theory."

The team also described the oddball pair's history. This binary system began with one star about twice the mass of the Sun and a second star slightly less massive than the Sun. The more massive star was the first to evolve, becoming a white dwarf weighing perhaps one-third as much as the Sun. Ten billion years later, its companion became another white dwarf. In each step, the puffed-up outer layers of the evolving star enveloped the companion, causing friction that moved the two stars closer together. They now orbit each other every 7.6 hours at a distance of about 650,000 miles and a stunning speed of 335,000 miles per hour.

"The relation between our white dwarf and its companion is like a cosmic marriage in which both people have to give a lot," said Kilic. "Two stars start out close to each other. One of them engulfs the other (like a hug) and gives continuously (losing mass), and they get closer. Then the other star evolves and becomes a giant and engulfs the first star (hugging back) and now it has to give a lot, or lose a lot of mass. They get closer and closer and end up dancing continuously."

The astronomers predict that the two white dwarfs eventually will merge. However, that merger will not take place for 10 billion years or more.

Key observations were made with the MMT Observatory in Arizona, which is operated jointly by the Smithsonian Astrophysical Observatory and the University of Arizona

One of the largest panoramic images ever taken with Hubble's cameras has been released to celebrate the 17th anniversary of the launch and deployment of the NASA/ESA Hubble Space Telescope. The image shows a 50 light-year-wide view of the tumultuous central region of the Carina Nebula where a maelstrom of star birth - and death - is taking place.

Hubble's new view of the Carina Nebula shows the process of star birth at a new level of detail. The bizarre landscape of the nebula is sculpted by the action of outflowing winds and scorching ultraviolet radiation from the monster stars that inhabit this inferno. These stars are shredding the surrounding material that is the last vestige of the giant cloud from which the stars were born.

This immense nebula contains a dozen or more brilliant stars that are estimated to be at least 50 to 100 times the mass of our Sun. The most opulent is the star eta Carinae, seen at far left. Eta Carinae is in the final stages of its brief eruptive lifespan, as shown by two billowing lobes of gas and dust that presage its upcoming explosion as a titanic supernova.

A series of so-called Bok globules from a mosaic of the Carina Nebula assembled from 48 frames taken with Hubble's Advanced Camera for Surveys. The island-like clumps of dark clouds scattered across the nebula are nodules of dust and gas that have so far resisted being eaten away by photoionisation. Credit: NASA, ESA, N. Smith (University of California, Berkeley), and The Hubble Heritage Team (STScI/AURA)

The fireworks in the Carina region started three million years ago when the nebula's first generation of newborn stars condensed and ignited in the middle of a huge cloud of cold molecular hydrogen. Radiation from these stars carved out an expanding bubble of hot gas. The island-like clumps of dark clouds scattered across the nebula are nodules of dust and gas that have so far resisted being eaten away by photoionisation.

The hurricane-strength blast of stellar winds and blistering ultraviolet radiation within the cavity is now compressing the surrounding walls of cold hydrogen. This is triggering a second stage of new star formation.

Our Sun and Solar System may have been born inside such a cosmic crucible 4.6 billion years ago. In looking at the Carina Nebula we are seeing star formation as it commonly occurs along the dense spiral arms of a galaxy.

This immense nebula is an estimated 7,500 light-years away in the southern constellation Carina, the Keel of the old southern constellation Argo Navis, the ship of Jason and the Argonauts from Greek mythology.

This image is an immense (29,566 x 14,321 pixels) mosaic of the Carina Nebula assembled from 48 frames taken with Hubble's Advanced Camera for Surveys. The Hubble images were taken in the light of ionized hydrogen. Colour information was added with data taken at the Cerro Tololo Inter- American Observatory in Chile. Red corresponds to sulphur, green to hydrogen, and blue to oxygen emission.

These three snapshots reveal nuggets of cold molecular hydrogen in the Carina Nebula. Credit: NASA, ESA, N. Smith (University of California, Berkeley), and The Hubble Heritage Team (STScI/AURA)

In its 17 years of exploring the heavens, NASA's Hubble Space Telescope has made nearly 800,000 observations and snapped nearly 500,000 images of more than 25,000 celestial objects. Hubble does not travel to stars, planets and galaxies. It takes pictures of them as it whirls around Earth at 17,500 miles an hour. In its 17-year lifetime, the telescope has made nearly 100,000 trips around our planet. Those trips have racked up plenty of frequent-flier-miles, about 2.4 billion, which is the equivalent of a round trip to Saturn.

The 17 years' worth of observations has produced more than 30 terabytes of data, equal to about 25 percent of the information stored in the Library of Congress.

Each day the orbiting observatory generates about 10 gigabytes of data, enough information to fill the hard drive of a typical home computer in two weeks.

The Hubble archive sends about 66 gigabytes of data each day to astronomers throughout the world.

Astronomers using Hubble data have published nearly 7,000 scientific papers, making it one of the most productive scientific instruments ever built.

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

The next 11-year cycle of solar storms will most likely start next March and peak in late 2011 or mid-2012 - up to a year later than expected - according to a forecast issued by the NOAA Space Environment Center in coordination with an international panel of solar experts. The NOAA Space Environment Center led the prediction panel and issued the forecast at its annual Space Weather Workshop in Boulder, Colo. NASA sponsored the panel.

The solar cycle. Credit: NOAA

Expected to start last fall, the delayed onset of Solar Cycle 24 stymied the panel and left them evenly split on whether a weak or strong period of solar storms lies ahead, but neither group predicts a record-breaker.

During an active solar period, violent eruptions occur more often on the sun. Solar flares and vast explosions, known as coronal mass ejections, shoot energetic photons and highly charged matter toward Earth, jolting the planet's ionosphere and geomagnetic field, potentially affecting power grids, critical military and airline communications, satellites, Global Positioning System (GPS) signals, and even threatening astronauts with harmful radiation. These same storms illuminate night skies with brilliant sheets of red and green known as auroras, or the northern or southern lights.

Solar cycle intensity is measured in maximum number of sunspots-dark blotches on the sun that mark areas of heightened magnetic activity. The more sunspots there are, the more likely it is that major solar storms will occur.

In the cycle forecast issued Wednesday, half of the panel predicts a moderately strong cycle of 140 sunspots, plus or minus 20, expected to peak in October 2011. The other half predicts a moderately weak cycle of 90 sunspots, plus or minus 10, peaking in August 2012. An average solar cycle ranges from 75 to 155 sunspots. The late decline of Cycle 23 has helped shift the panel away from its earlier leaning toward a strong Cycle 24. Now the group is evenly split between strong and weak.

The first year after solar minimum, marking the end of Cycle 23, will provide the information scientists need to arrive at a consensus. NOAA and the panel decided to issue their best estimate now and update the forecast as the cycle progresses, since NOAA Space Environment Center customers have been requesting a forecast for more than a year.

"By giving a long-term outlook, we're advancing a new field-space climate-that's still in its infancy," said retired Air Force Brig. Gen. David L. Johnson, director of the NOAA National Weather Service. "Issuing a cycle prediction of the onset this far in advance lies on the very edge of what we know about the sun."

Scientists have issued cycle predictions only twice before. In 1989, a panel met to predict Cycle 22, which peaked that same year. Scientists met again in September of 1996 to predict Cycle 23-six months after the cycle had begun. Both groups did better at predicting timing than intensity, according to NOAA Space Environment Center scientist Douglas Biesecker, who chairs the current panel. He describes the group's confidence level as "high" for its estimate of a March 2008 onset and "moderate" overall for the two estimates of peak sunspot number and when those peaks would occur.

One disagreement among the current panel members centers on the importance of magnetic fields around the sun's poles as the previous cycle decays. End-cycle polar fields are the bedrock of the approach predicting a weak Cycle 24. The strong-cycle forecasters place more importance on other precursors extending over a several-cycle history. Another clue will be whether Cycle 24 sunspots appear by mid 2008. If not, the strong-cycle group might change its forecast.

"The panelists in each camp have clear views on why they believe in their prediction, why they might be wrong, and what it would take to change their minds," said Biesecker. "We're on the verge of understanding and agreeing on which precursors are most important in predicting future solar activity."

The NOAA Space Environment Center is the nation's first alert of solar activity and its affects on Earth. Just as NOAA's hurricane experts predict the upcoming season of Atlantic storms and forecast individual hurricanes, the agency's space weather experts issue outlooks for the next 11-year solar cycle and warn of storms occurring on the sun that could impact Earth. Both the NOAA National Hurricane Center and NOAA Space Environment Center are among nine NOAA National Centers for Environmental Prediction, part of the NOAA National Weather Service. The NOAA Space Environment Center also is the world warning agency of the International Space Environment Service, a consortium of 11 member nations.

NOAA, an agency of the U.S. Commerce Department, is celebrating 200 years of science and service to the nation. From the establishment of the Survey of the Coast in 1807 by Thomas Jefferson to the formation of the Weather Bureau and the Commission of Fish and Fisheries in the 1870s, much of America's scientific heritage is rooted in NOAA. NOAA is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and information service delivery for transportation, and by providing environmental stewardship of the nation's coastal and marine resources. Through the emerging Global Earth Observation System of Systems (GEOSS), NOAA is working with its federal partners, more than 60 countries and the European Commission to develop a global monitoring network that is as integrated as the planet it observes, predicts and protects.

Hawking enjoys zero GBY WILLIAM HARWOODSTORY WRITTEN FOR CBS NEWS "SPACE PLACE" & USED WITH PERMISSIONPosted: April 26, 2007

Physicist Stephen Hawking, the wheelchair-bound theorist known for his insights into the nature of black holes and gravity, experienced weightlessness today during an eagerly anticipated airplane ride off Florida's East Coast.

Credit: Zero Gravity Corp.

Attended by a team of physicians, nurses and supporters, Hawking enjoyed 20 to 25 seconds of weightlessness during eight parabolic arcs aboard the Zero Gravity Corp.'s Boeing 727 jet. Passengers on such flights are weightlessness as they "fall" toward Earth inside the plane's foam-padded interior.

At the bottom of each arc, the nose of the plane is pulled up, briefly subjecting the passengers to about 1.5 times the force of gravity. Hawking, who suffers from amyotrophic lateral sclerosis, or ALS - Lou Gehrigs Disease - was closely monitored throughout the afternoon flight. After returning to the Kennedy Space Center's shuttle runway, he was all smiles and officials said he enjoyed the ride.

"Many people have asked me why I am taking this flight," the renowned physicist told reporters earlier today at the Shuttle Landing Facility. "I am doing it for many reasons. First of all, I believe that life on Earth is at an ever increasing risk of being wiped out by a disaster, such as sudden global warming, nuclear war, a genetically engineered virus or other dangers.

"I think the human race has no future if it doesn't go into space. I therefore want to encourage public interest in space," he said, speaking through a computer in his famously robotic "voice." "I have long wanted to go into space and the zero gravity flight is a first step toward space travel. I also want to demonstrate to the public that everyone can participate in this type of weightless experience."

Peter Diamandidis, president of Zero Gravity Corp., said the flight was organized to benefit four charities - Easter Seals, the Starlight Starbright Children's Foundation, Augie's Quest and the X Prize Foundation. Eight seats were auctioned off, raising some $150,000. Rides on the plane normally sell for $3,500 per passenger.

"We're really excited," Diamandis said. "The entire team is pumped and ready to go to fulfill his dream of being weightless."

To ensure's Hawking's safety, the physicist was closely monitored by his personal team of physicians and nurses. During a test flight Wednesday using an eighth grade student as a stand in, the team perfected the way they will gently lower Hawking to the padded floor after each parabola to make sure he remains comfortable during the half-minute or so when he will be subjected to 1.5 times the normal force of gravity.

"We've done a tremendous amount to ensure safety on this flight," Diamandis said. "We feel we have an excellent safety plan."

Diamandis said Hawking's doctors planned to assess blood pressure, oxygen levels and other factors after the first parabola to make sure it is safe to proceed. Diamandis said he would be happy with a single parabola, prompting Hawking to interject a computer-synthesized "no!"

"As you can imagine, I am very excited," Hawking said earlier. "I have been wheelchair bound for almost four decades and the chance to float free in zero G will be wonderful."

Hawking is considered one of the world's leading authorities on quantum black holes and big bang cosmology. Along with his scholarly achievements, Hawking is the author of the popular bestseller "A Brief History of Time."

Black holes may fill the universe with seeds of lifeHARVARD-SMITHSONIAN CENTER FOR ASTROPHYSICS NEWS RELEASEPosted: April 30, 2007

CAMBRIDGE, MA - New research shows that black holes are not the ultimate destroyers that are often portrayed in popular culture. Instead, warm gas escaping from the clutches of enormous black holes could be one source of the chemical elements that make life possible.

The black hole at the center of the NGC 4051 galaxy emits a hot wind of chemical elements, including elements like carbon and oxygen that are critical for life. The hot wind originates very close to the black hole, at a distance about five times the size of Neptune's orbit. Although speedy, the wind is weaker than expected and ejects only 2 to 5 percent of accreting material. Credit: George Seitz/Adam Block/NOAO/AURA/NSF

Immediately after the Big Bang, the universe contained only hydrogen and helium. Heavier chemical elements had to be cooked up inside the first stars, then scattered throughout space to be incorporated in next-generation stars and their planets. Black holes may have helped to distribute those elements across the cosmos.

Black holes are not all-consuming monsters. Until gas crosses the boundary known as the event horizon, it can still escape if it is heated sufficiently.

"One of the big questions in cosmology is how much influence massive black holes exert on their surroundings," said co-author Martin Elvis of the Harvard-Smithsonian Center for Astrophysics (CfA). "This research helps answer that question."

An international team of astronomers has found that hot winds from giant black holes in galactic centers may blow heavy elements like carbon and oxygen into the vast tracts of space between galaxies.

The team, led by Yair Krongold of the Universidad Nacional Autonoma de Mexico, studied the supermassive black hole at the center of the galaxy NGC 4051. They found that gas was escaping from much closer to the black hole than previously thought. The outflow source is located about 2,000 Schwarzschild radii from the black hole, or about five times the size of Neptune's orbit. (The Schwarzschild radius is the black hole's "point of no return" - about 4 million miles for the black hole in NGC 4051.)

The team could also determine the fraction of gas that was avoiding being swallowed. That fraction ended up being smaller than earlier studies suggested.

"We calculate that between 2 to 5 percent of the accreting material is flowing back out," says team member Fabrizio Nicastro of the CfA.

Winds from black holes have been clocked at speeds of up to 4 million miles per hour. Over thousands of years, the chemical elements such as carbon and oxygen in those winds can travel immense distances, eventually becoming incorporated into the cosmic clouds of gas and dust, called nebulae, that will form new stars and planets.

This research, which used data from the European Space Agency's XMM-Newton satellite, is being reported in the April 20 issue of The Astrophysical Journal.

CAMBRIDGE, MA - Two rambunctious young stars are destroying their natal dust cloud with powerful jets of radiation, in an infrared image from NASA's Spitzer Space Telescope. The stars are located approximately 600 light-years away in a cosmic cloud called BHR 71.

"BHR 71 has been a favorite object of mine for years," said Tyler Bourke of the Harvard-Smithsonian Center for Astrophysics. "This spectacular new Spitzer image really shows off the changes in the jets, in ways impossible at other wavelengths."

The visible light image (left) was taken by the European Space Agency's ground-based Very Large Telescope. In this image BHR 71 is just a large black structure. The burst of yellow light toward the bottom of the cloud is the only indication that stars might be forming inside.

In the infrared image (middle), the baby stars are shown as the bright yellow smudges toward the center. Both of these yellow spots have wisps of green shooting out of them. The green wisps reveal the beginning of a jet. Like a rainbow, the jet begins as green, then transitions to orange, and red toward the end.

The jets' changing colors reveals a cooling effect, and may suggest that the young stars are spouting out radiation in regular bursts. The green tints at the beginning of the jet reveal really hot hydrogen gas, the orange shows warm gas, and the wisps of red at the end represent the coolest gas.

The fact that gas toward the beginning of the jet is hotter than gas near the middle, suggests that the stars must give off regular bursts of energy - and the material closest to the star is being heated by shockwaves from a recent stellar outburst. Meanwhile, the tints of orange reveal gas that is currently being heated by shockwaves from a previous stellar outburst. By the time these shockwaves reach the end of the jet, they have slowed down so significantly that the gas is only heated a little, and looks red.

The combined visible-light infrared composite (right) shows that a young star's powerful jet is responsible for the rupture at the bottom of the dense cloud in the visible-light image. We know this because the burst of light in the visible-light image overlaps exactly with a jet spouting out of the left star, shown in the infrared image.

The combination of views also brings out some striking details that evaded visible-light detection. For example, the yellow dots scattered throughout the image are actually young stars forming inside BHR 71. Spitzer also uncovered another young star with jets, located to the right of the powerful jet seen in the visible-light image.

Spitzer can see details, that visible-light telescopes don't, because its infrared instruments are sensitive to "heat."

The infrared image is made up of data from Spitzer's infrared array camera. Blue shows infrared light at 3.6 microns, green is light at 4.5 microns, and red is light at 8.0 microns.

John Longhi has pondered magma formation in the Moon for a long time, basing his work on careful experiments at high pressure and temperature, computer calculations based on the results of those experiments, and a vast knowledge of phase equilibria (what happens when rocks melt and crystallize). One of his interests has been the origin of the magma that produced the Apollo 15 green glass, a volcanic deposit. The green glass is what cosmochemists call "primitive," which means that it was not altered as it migrated from deep in the Moon to the surface. Thus, it reflects the composition of the lunar interior in the region where it formed.

lunar green glass

Spherules of green glass (most about 0.1 millimeter across) collected during the Apollo 15 mission. The spherules formed by fire fountaining, a type of volcanic eruption in which escaping gases disrupt the magma into countless droplets of magma (see PSRD article: Explosive Volcanic Eruptions on the Moon). The Apollo 15 green glass magma was modified only slightly if at all from the region of the lunar mantle in which it formed, so its composition provides a window to at least some parts of the lunar interior.

A NASA satellite has captured the first occurrence this summer of mysterious shiny polar clouds that form 50 miles above Earth’s surface.

FEATURE NASA Satellite Captures First View of 'Night-Shining Clouds'

06.28.07

A NASA satellite has captured the first occurrence this summer of mysterious shiny polar clouds that form 50 miles above Earth’s surface.

One of the first ground sightings of noctilucent clouds in the 2007 season.Click image to enlarge.

Image above: This image shows one of the first ground sightings of noctilucent clouds in the 2007 season. Credit: Veres Viktor of Budapest, Hungary taken on June 15, 2007.

The first observations of these "night-shining" clouds by a satellite named "AIM" which means Aeronomy of Ice in the Mesosphere, occurred above 70 degrees north latitude on May 25. People on the ground began seeing the clouds on June 6 over Northern Europe. AIM is the first satellite mission dedicated to the study of these unusual clouds.

These mystifying clouds are called Polar Mesospheric Clouds, or PMCs, when they are viewed from space and referred to as "night-shining" clouds or Noctilucent Clouds, when viewed by observers on Earth. The clouds form in an upper layer of the Earth’s atmosphere called the mesosphere during the Northern Hemisphere’s summer season which began in mid-May and extends through the end of August and are being seen by AIM’s instruments more frequently as the season progresses. They are also seen in the high latitudes during the summer months in the Southern Hemisphere.

Image above: On June 11, 2007 the cameras on the AIM satellite returned some of the first data documenting noctilucent clouds over the Arctic regions of Europe and North America. This new data reveals the global extent and structure of these mysterious clouds, to a degree that was previously unattainable. White and light blue represent noctilucent cloud structures. Black indicates areas where no data is available. Credit: Cloud Imaging and Particle Size Experiment data processing team at the University of Colorado Laboratory for Atmospheric and Space Physics

Very little is known about how these clouds form over the poles, why they are being seen more frequently and at lower latitudes than ever before, or why they have been growing brighter. AIM will observe two complete cloud seasons over both poles, documenting an entire life cycle of the shiny clouds for the first time.

"It is clear that these clouds are changing, a sign that a part of our atmosphere is changing and we do not understand how, why or what it means," stated AIM principal investigator James Russell III of Hampton University, Hampton, Va. "These observations suggest a connection with global change in the lower atmosphere and could represent an early warning that our Earth environment is being changed."

AIM is providing scientists with information about how many of these clouds there are around the world and how different they are including the sizes and shapes of the tiny particles that make them up. Scientists believe that the shining clouds form at high latitudes early in the season and then move to lower latitudes as time progresses. The AIM science team is studying this new data to understand why these clouds form and vary, and if they may be related to global change.

Once the summer season ends in the Northern Hemisphere around mid- to late August, the Southern Hemisphere spring season starts about three months later in the period around mid- to late November. AIM will then be watching for shining clouds in the Southern Hemisphere from November through mid-March when that season ends.

AIM and is managed at Goddard Space Flight Center, Greenbelt, Md and the AIM Project Data Center is located at Hampton University.

Cynthia O'CarrollGoddard Space Flight Center

« Last Edit: 18/07/2007 22:32:20 by Karen W. »

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"Life is not measured by the number of Breaths we take, but by the moments that take our breath away."

BERKELEY -- An exploding star first observed last September is the largest and most luminous supernova ever seen, according to University of California, Berkeley, astronomers, and may be the first example of a type of massive exploding star rare today but probably common in the very early universe.

Unlike typical supernovas that reach a peak brightness in days to a few weeks and then dim into obscurity a few months later, SN2006gy took 70 days to reach full brightness and stayed brighter than any previously observed supernova for more than three months. Nearly eight months later, it still is as bright as a typical supernova at its peak, outshining its host galaxy 240 million light years away.

UC Berkeley post-doctoral fellows Nathan Smith and David Pooley estimate the star's mass at between 100 and 200 times that of the sun. Such massive stars are so rare that galaxies like our own Milky Way may contain only a dozen out of a stellar population of 400 billion.

"This was a truly monstrous explosion, a hundred times more energetic than a typical supernova," said Smith, who led a team of astronomers from UC Berkeley and the University of Texas. "That means the star that exploded might have been as massive as a star can get, about 150 times that of our sun. We've never seen that before."

"Of all exploding stars ever observed, this was the king," said Alex Filippenko, UC Berkeley astronomer and leader of the ground-based observations at the University of California's Lick Observatory in California and the W. M. Keck Observatory in Hawaii. "We were astonished to see how bright it got, and how long it lasted."

This artist's illustration shows what the brightest supernova ever recorded, known as SN 2006gy, may have looked like. The fireworks-like material (white) shows the explosive death of an extremely massive star. Before it exploded, the star expelled the lobes of cool gas (red). As the material from the explosion crashes into the lobes, it heats the gas in a shock front (green, blue and yellow) and pushes it backward. Credit: NASA/CXC/M.Weiss

Based on the Lick and Keck observations, plus data from the Chandra X-ray Observatory, Smith, Pooley, Filippenko and their colleagues argue that the stellar explosion was not your run-of-the-mill supernova, but a possible pair-instability supernova. They have submitted a paper describing the discovery and their conclusions to The Astrophysical Journal.

Stars with masses at least 10 times greater than our sun end their lives after burning hydrogen to helium, helium to carbon, and on to larger elements until they reach iron, when fusion stops. Toward the end of this process, the heat produced in the core of the star becomes insufficient to support the outer layers, which collapse inward, finishing the fusion process and crunching the core to a neutron star or black hole. The outer layers of the star are blown off in a bright flare-up we observe as a supernova.

For stars much more massive than this, ranging from 140 solar masses to as many as 250, the temperature at the core becomes so great that before the fusion cascade is complete, high-energy gamma rays in the core start annihilating one another, creating matter-antimatter pairs, mostly electron-positron pairs. Since gamma radiation is the energy that prevents collapse of the outer layers of the star, once the radiation starts disappearing, the outer layers fall inward. The net result is a thermonuclear explosion that, theoretically, would be brighter than any typical supernova. In this type of supernova, the star is blown to smithereens, leaving behind no black hole.

"This discovery forces us to go back to the drawing board to understand how the most massive stars die," Smith said. "Instead of just winking away into a black hole, they apparently can suffer these brilliant explosions that can be seen far across the universe. The fact that this thing is so bright, and stayed bright for a long time, makes our chances of detecting them in the early universe much better."

This graphic gives a summary of our best current understanding of the evolution of stars, showing their birth, middle age and eventual demise. Credit: NASA/CXC/M.Weiss

Such pair-instability supernovas should theoretically produce a greater percentage of heavy elements. According to Smith, the radioactive decay of nickel-56 produces most of the light of a supernova, and this pair-instability supernova produced about 20 solar masses of nickel, compared to maybe 0.6 solar masses in a Type Ia supernova. Astronomers think that a large proportion of the universe's first stars were supermassive stars like this that, upon exploding, seeded the early universe with the heavy elements from which planets and later, humans, were made.

"We may have witnessed a modern-day version of how the first generation of the most massive stars ended their lives, when the universe was very young," Filippenko said.

The star that produced SN 2006gy apparently expelled a large amount of mass prior to exploding, reminiscent of the star eta Carinae, a so-called luminous blue variable which, at 100 to 120 solar masses, is the most massive star in our galaxy.

"This is also very exciting because it suggests that eta Carinae, only 7,500 light years away, might possibly explode in a similar manner, becoming a spectacularly bright star in our sky," Filippenko said.

"We don't know for sure if Eta Carinae will explode soon, but we had better keep a close eye on it just in case," added Mario Livio of the Space Telescope Science Institute in Baltimore, Md., who was not involved in the research. "Eta Carinae's explosion could be the best star-show in the history of modern civilization

Estimated to be 100 times heftier than our Sun, Eta Carinae is one of the most massive stars in our galaxy. It may also turn out to be one of the shortest-lived, because results for SN 2006gy suggest that it may be destroyed by a supernova at any time. This Hubble telescope image of Eta Carinae shows a huge, billowing pair of gas and dust clouds, caused by a giant eruption about 160 years ago, when it became one of the brightest stars in the southern sky. Credit: NASA/N.Smith & J.Morse

University of Texas graduate student Robert Quimby first observed the supernova on Sept. 18, 2006 in the galaxy NGC 1260, located in the constellation Perseus. Filippenko's team immediately began observing it with its dedicated supernova search and monitor telescope at Lick, the Katzman Automatic Imaging Telescope.

Filippenko and his graduate student Ryan Foley subsequently obtained spectra of the star using the Lick 3-meter Shane telescope and the DEIMOS spectrograph mounted on the Keck II telescope.

Pooley led the Chandra observation, which allowed the team to rule out the most likely alternative explanation for the supernova, namely that it was an explosion of a white dwarf star into a dense, hydrogen-rich environment.

"If that were the case, this supernova would have been 1,000 times brighter in X-rays than what we detected with Chandra," said Pooley. "This must have been an extremely massive star."

"In terms of the effect on the early universe, there's a huge difference between these two possibilities," said Smith. "One pollutes the galaxy with large quantities of newly synthesized elements, and the other locks them up forever in a black hole."

"One exciting repercussion of this is that, if pair-instability supernovas really are this bright, it gives us hope that the James Webb Space Telescope might actually be able to detect these explosions from the first stars, thereby verifying that they may actually exist," he added.

The results from Smith, Pooley, Filippenko and their colleagues, including Weidong Li, Ryan Chornock, Jeffrey M. Silverman, Joshua S. Bloom and Charles Hansen of UC Berkeley and J. Craig Wheeler of the University of Texas, will appear in The Astrophysical Journal.

NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the agency's Science Mission Directorate. The work also was supported by the National Science Foundation and the W. M. Keck Foundation

An international team of astronomers using the NASA/ESA Hubble Space Telescope has discovered a ghostly ring of dark matter that was formed long ago during a titanic collision between two massive galaxy clusters. It is the first time that a dark matter distribution has been found that differs substantially from the distribution of ordinary matter.

Astronomers have long suspected the existence of the invisible substance of dark matter as the source of additional gravity that holds together galaxy clusters. Otherwise, astronomers say, the clusters would fly apart if they relied only on the gravity from their visible stars. Although astronomers don't know what dark matter is made of, they hypothesize that it is a type of elementary particle that pervades the Universe.

In a result just published, astronomers using the NASA/ESA Hubble Space Telescope report the discovery of a ring of dark matter in the cluster ZwCl0024+1652. The ring's discovery is among the strongest evidence yet that dark matter exists.

"This is the first time we have detected dark matter as having a unique structure that is different from the gas and galaxies in the cluster," said astronomer M. James Jee of Johns Hopkins University in Baltimore, USA, a member of the team that spotted the dark matter ring.

The ring, which measures 2.6 million light-years across, was found in the cluster ZwCl0024+1652, located 5 billion light-years away from Earth. The team found the ring unexpectedly while they were mapping the distribution of dark matter within the cluster. Although astronomers cannot see dark matter, they can infer its existence in galaxy clusters by observing how its gravity bends the light of more distant background galaxies.

"Although the invisible matter has been found before in other galaxy clusters, it has never been detected to be so largely separated from the hot gas and the galaxies that make up galaxy clusters," Jee continued. "By seeing a dark matter structure that is not traced by galaxies and hot gas, we can study how it behaves differently from normal matter."

During the team's dark-matter analysis, they noticed a ripple in the mysterious substance, somewhat like the ripples created in a pond from a stone plopping into the water.

"I was annoyed when I saw the ring because I thought it was an artifact, which would have implied a flaw in our data reduction," Jee explained. "I couldn't believe my result. But the more I tried to remove the ring, the more it showed up. It took more than a year to convince myself that the ring was real. I've looked at a number of clusters and I haven't seen anything like this."

Curious about why the ring was in the cluster and how it had formed, Jee found previous research that suggested the cluster had collided with another cluster 1 to 2 billion years ago. The research, published in 2002 by Oliver Czoske of the Argelander-Institut für Astronomie at Bonn University, was based on spectroscopic observations of the cluster's three-dimensional structure. The study revealed two distinct groupings of galaxies clusters, indicating a collision between both clusters.

Massive Jupiter is undergoing dramatic atmospheric changes that have never been seen before with the keen "eye" of NASA's Hubble Space Telescope.

Jupiter's turbulent clouds are always changing as they encounter atmospheric disturbances while sweeping around the planet at hundreds of miles per hour. But these Hubble images reveal a rapid transformation in the shape and color of Jupiter's clouds near the equator, marking an entire face of the globe.

The planet is wrapped in bands of yellows, browns, and whites. These bands are produced by the atmosphere flowing in different directions at various latitudes. Lighter-hued areas where the atmosphere rises are called zones. Darker regions where the atmosphere falls are called belts. When these opposing flows interact, storms and turbulence appear.

Between March 25 and June 5, Hubble's Wide Field and Planetary Camera 2 captured entire bands of clouds changing color. Zones have darkened into belts and belts have lightened and transformed into zones. Cloud features have rapidly altered in shape and size.

The image at left shows a thin band of white clouds above Jupiter's equator. The white color indicates clouds at higher altitudes in Jupiter's atmosphere. In the image at right, the band's white hue has turned brown, showing clouds deep within the planet's atmosphere. The whole band appears to have merged with the one below it.

In the same cloud band above the equator, the small swirls in the left-hand image have morphed into larger wave-like features in the right-hand photo. Dominating the band is a dark streak that resembles a snake. This serpent-shaped structure is actually a small tear in the cloud deck, which gives astronomers a view deep within the atmosphere.

Below the equatorial region, the brownish upside-down shark fin in the left-hand image disappears in the photo at right. Appearing instead are brownish tongue-shaped clouds with a stream of white swirls below them.

These global upheavals have been seen before, but not with Hubble's sharp resolution. Astronomers using ground-based telescopes first spied drastic atmospheric transformation in the 1980s. Another major disturbance was seen in the early 1990s, after Hubble was launched into space. The telescope, however, did not have the resolution to view the upheaval in fine detail. These higher-quality Hubble images may help astronomers understand how such global upheavals develop on Jupiter.

Nearly 12.5 million light-years away in the dwarf galaxy NGC 4449 a veritable stellar "fireworks" is on display - here shown in exquisite detail through the eyes of the Hubble Space Telescope.

Hundreds of thousands of vibrant blue and red stars are visible in this new image of galaxy NGC 4449 taken by the NASA/ESA Hubble Space Telescope. Hot bluish white clusters of massive stars are scattered throughout the galaxy, interspersed with numerous dustier reddish regions of current star formation. Massive dark clouds of gas and dust are silhouetted against the flaming starlight.

NGC 4449 has been forming stars since several billion years ago, but currently it is experiencing a star formation event at a much higher rate than in the past. This unusual explosive and intense star formation activity qualifies as a starburst. At the current rate, the gas supply that feeds the stellar production would only last for another billion years or so.

Starbursts usually occur in the central regions of galaxies, but NGC 4449 has a more widespread star formation activity, since the very youngest stars are observed both in the nucleus and in streams surrounding the galaxy.

A "global" starburst like NGC 4449 resembles primordial star forming galaxies which grew by merging with and accreting smaller stellar systems. Since NGC 4449 is close enough to be observed in great detail, it is the ideal laboratory for the investigation of what may have occurred during galactic formation and evolution in the early Universe.

It's likely that the current widespread starburst was triggered by interaction or merging with a smaller companion. NGC 4449 belongs to a group of galaxies in the constellation Canes Venatici, the Hunting Dogs. Astronomers think that NGC 4449's star formation has been influenced by interactions with several of its neighbours.

This image was taken in November 2005 by an international science team led by Alessandra Aloisi of European Space Agency (ESA)/the Space Telescope Science Institute (STScI) in Baltimore. Other team members include Francesca Annibali (STScI), Claus Leitherer (STScI), Jennifer Mack (STScI), Marco Sirianni (ESA/STScI), Monica Tosi (INAF-OAB), and Roeland van der Marel (STScI).

How many stars does it take to "raise" a planet? In our own solar system, it took only one -- our Sun. However, new research from NASA's Spitzer Space Telescope shows that planets might sometimes form in systems with as many as four stars.

This artist concept depicts a quadruple-star system called HD 98800. The system is approximately 10 million years old, and is located 150 light-years away in the constellation TW Hydrae. Credit: NASA/JPL-Caltech/T. Pyle (SSC)

Astronomers used Spitzer's infrared vision to study a dusty disk that swirls around a pair of stars in the quadruple-star system HD 98800. Such disks are thought to give rise to planets. Instead of a smooth, continuous disk, the telescope detected gaps that could be caused by a unique gravitational relationship between the system's four stars. Alternatively, the gaps could indicate planets have already begun to form, carving out lanes in the dust.

"Planets are like cosmic vacuums. They clear up all the dirt that is in their path around the central stars," said Dr. Elise Furlan, of the NASA Astrobiology Institute at the University of California at Los Angeles. Furlan is the lead author of a paper that has been accepted for publication in The Astrophysical Journal.

HD 98800 is approximately 10 million years old, and is located 150 light-years away in the constellation TW Hydrae.

Before Spitzer set its gaze on HD 98800, astronomers had a rough idea of the system's structure from observations with ground-based telescopes. They knew the system contains four stars, and that the stars are paired off into doublets, or binaries. The stars in the binary pairs orbit around each other, and the two pairs also circle each other like choreographed ballerinas. One of the stellar pairs, called HD 98800B, has a disk of dust around it, while the other pair has none.

Although the four stars are gravitationally bound, the distance separating the two binary pairs is about 50 astronomical units (AU) -- slightly more than the average distance between our Sun and Pluto. Until now, technological limitations have hindered astronomers' efforts to look at the dusty disk around HD 98800B more closely.

With Spitzer, scientists finally have a detailed view. Using the telescope's infrared spectrometer, Furlan's team sensed the presence of two belts in the disk made of large dust grains. One belt sits at approximately 5.9 AU away from the central binary, HD 98800B, or about the distance from the Sun to Jupiter. This belt is likely made up of asteroids or comets. The other belt sits at 1.5 to 2 AU, comparable to the area where Mars and the asteroid belt sit, and probably consists of fine grains.

"Typically, when astronomers see gaps like this in a debris disk, they suspect that a planet has cleared the path. However, given the presence of the diskless pair of stars sitting 50 AU away, the inward-migrating dust particles are likely subject to complex, time-varying forces, so at this point the existence of a planet is just speculation," said Furlan.

Astronomers believe that planets form like snowballs over millions of years, as small dust grains clump together to form larger bodies. Some of these cosmic rocks then smash together to form rocky planets, like Earth, or the cores of gas-giant planets like Jupiter. Large rocks that don't form planets often become asteroids and comets. As these rocky structures violently collide, bits of dust are released into space. Scientists can see these dust grains with Spitzer's supersensitive infrared eyes.

According to Furlan, the dust generated from the collision of rocky objects in the outer belt should eventually migrate toward the inner disk. However, in the case of HD 98800B, the dust particles do not evenly fill out the inner disk as expected, due to either planets or the diskless binary pair sitting 50 AU away and gravitationally influencing the movement of dust particles.

"Since many young stars form in multiple systems, we have to realize that the evolution of disks around them and the possible formation of planetary systems can be way more complicated and perturbed than in a simple case like our solar system," Furlan added.

PASADENA, Calif. - Cassini scientists may have identified the source of one of Saturn's more mysterious rings. Saturn's G ring likely is produced by relatively large, icy particles that reside within a bright arc on the ring's inner edge.

Credit: NASA/JPL/Space Science Institute

The particles are confined within the arc by gravitational effects from Saturn's moon Mimas. Micrometeoroids collide with the particles, releasing smaller, dust-sized particles that brighten the arc. The plasma in the giant planet's magnetic field sweeps through this arc continually, dragging out the fine particles, which create the G ring.

The finding is evidence of the complex interaction between Saturn's moons, rings and magnetosphere. Studying this interaction is one of Cassini's objectives. The study is in the Aug. 2 issue of the journal Science and was based on observations made by multiple Cassini instruments in 2004 and 2005.

"Distant pictures from the cameras tell us where the arc is and how it moves, while plasma and dust measurements taken near the G ring tell us how much material is there," said Matthew Hedman, a Cassini imaging team associate at Cornell University in Ithaca, N.Y., and lead author on the Science paper.

Saturn's rings are an enormous, complex structure, and their origin is a mystery. The rings are labeled in the order they were discovered. From the planet outward, they are D, C, B, A, F, G and E. The main rings -- A, B and C from edge-to-edge, would fit neatly in the distance between Earth and the moon. The most transparent rings are D -- interior to C -- and F, E and G, outside the main rings.

Unlike Saturn's other dusty rings, such as the E and F rings, the G ring is not associated closely with moons that either could supply material directly to it -- as Enceladus does for the E ring -- or sculpt and perturb its ring particles -- as Prometheus and Pandora do for the F ring. The location of the G ring continued to defy explanation, until now.

Cassini images show that the bright arc within the G ring extends one-sixth of the way around Saturn and is about 250 kilometers (155 miles) wide, much narrower than the full 5,955-kilometer width (3,700 miles) of the G ring. The arc has been observed several times since Cassini's 2004 arrival at the ringed planet and thus appears to be a long-lived feature. A gravitational disturbance caused by the moon Mimas exists near the arc.

As part of their study, Hedman and colleagues conducted computer simulations that showed the gravitational disturbance of Mimas could indeed produce such a structure in Saturn's G ring. The only other places in the solar system where such disturbances are known to exist are in the ring arcs of Neptune.

Cassini's magnetospheric imaging instrument detected depletions in charged particles near the arc in 2005. According to the scientists, unseen mass in the arc must be absorbing the particles. "The small dust grains that the Cassini camera sees are not enough to absorb energetic electrons," said Elias Roussos of the Max-Planck-Institute for Solar System Research, Germany, and member of the magnetospheric imaging team. "This tells us that a lot more mass is distributed within the arc."

The researchers concluded that there is a population of larger, as-yet-unseen bodies hiding in the arc, ranging in size from that of peas to small boulders. The total mass of all these bodies is equivalent to that of an ice-rich, small moon that's about 100 meters wide (328 feet wide).

Joe Burns, a co-author of the paper from Cornell University and a member of the imaging team, said, "We'll have a super opportunity to spot the G ring's source bodies when Cassini flies about 600 miles from the arc 18 months from now."

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, Pasadena, Calif., manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at the laboratory. The imaging team is based at the Space Science Institute, Boulder, Colo. The magnetospheric imaging instrument team is based at Johns Hopkins University, Laurel, Md.

A monster galaxy pileupYALE UNIVERSITY NEWS RELEASEPosted: August 6, 2007

NEW HAVEN, Conn. - Four galaxies are slamming into each other and kicking up billions of stars in one of the largest cosmic smash-ups ever observed.

The clashing galaxies, spotted by NASA's Spitzer Space Telescope and the WIYN Telescope, will eventually merge into a single, behemoth galaxy up to 10 times as massive as our own Milky Way. This rare sighting provides an unprecedented look at how the most massive galaxies in the universe form.

This artist's concept shows what the night sky might look like from a hypothetical planet around a star tossed out of the ongoing collision between big galaxies (yellow blobs). Credit: NASA/JPL-Caltech/Harvard-Smithsonian CfA

"Most of the galaxy mergers we already knew about are like compact cars crashing together," said Kenneth Rines of the Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass. "What we have here is like four sand trucks smashing together, flinging sand everywhere." Rines, who was a Mead postdoctoral fellow at Yale from 2003-6 when much of this work was done, is lead author of a paper accepted for publication in Astrophysical Journal Letters.

Collisions, or mergers, between galaxies are common in the universe. Gravity causes some galaxies that are close together to tangle and ultimately unite over a period of millions of years. Though stars in merging galaxies are tossed around like sand, they have a lot of space between them and survive the ride. Our Milky Way galaxy will team up with the Andromeda galaxy in five billion years.

Mergers between one big galaxy and several small ones, called minor mergers, are well documented. For example, one of the most elaborate known minor mergers is taking place in the Spiderweb galaxy - a massive galaxy that is catching dozens of small ones in its "web" of gravity. Astronomers have also witnessed "major" mergers among pairs of galaxies that are similar in size. But no major mergers between multiple hefty galaxies - the big rigs of the galaxy world - have been seen until now.

The new quadruple merger was discovered serendipitously during a survey of a distant cluster of galaxies, called CL0958+4702, located nearly five billion light-years away. The telescopes first spotted an unusually large fan-shaped plume of light coming out of a gathering of four blob-shaped, or elliptical, galaxies. Three of the galaxies are about the size of the Milky Way, while the fourth is three times as big.

"The colors from the WIYN and Spitzer data show that the stars are old, but the higher resolution WIYN images show that the light from the disrupted galaxy does not have small-scale structure but is instead smoothly distributed telling us that the galaxies involved in the merger are elliptical rather than spiral galaxies," said Jeffrey Kenney, professor and chair of Astronomy at Yale.

According to Kenney, WIYN (named for it¹s joint ownership by the University of Wisconsin, Indiana University, Yale University, and the National Optical Astronomy Observatory) is one of the best imaging telescopes in the world. "The sharpness of the WIYN images helps show that we are in fact seeing a merger, and what type of galaxies have merged."

"The WIYN telescope provides some of the sharpest images possible from ground-based telescopes. The WIYN images show that the four galaxies have well-defined cores that have held together during the merger, much like egg yolks stay together longer than egg whites if you "merge" them in a mixing bowl," said Rines.

Further analysis of the plume revealed that it is made up of billions of older stars flung out and abandoned in an ongoing clash. About half of the stars in the plume will later fall back into the galaxies. "When this merger is complete, this will be one of the biggest galaxies in the universe," said Rines.

One of the biggest galaxy collisions ever observed is taking place at the center of this image. The four yellow blobs in the middle are large galaxies that have begun to tangle and ultimately merge into a single gargantuan galaxy. Credit: NASA/JPL-Caltech/CXO/WIYN/Harvard-Smithsonian CfA

The Spitzer observations also show that the new merger lacks gas. Theorists predict that massive galaxies grow in a variety of ways, including gas-rich and gas-poor mergers. In gas-rich mergers, the galaxies are soaked with gas that ignites to form new stars. Gas-poor mergers lack gas, so no new stars are formed. Spitzer found only old stars in the quadruple encounter.

"The Spitzer data show that these major mergers are gas-poor, unlike most mergers we know about," said Rines. "The data also represent the best evidence that the biggest galaxies in the universe formed fairly recently through major mergers."

Some of the stars tossed out in the monstrous merger will live in isolated areas outside the borders of any galaxies. Such abandoned stars could theoretically have planets. If so, the planets' night skies would be quite different from our own, with fewer stars and more visible galaxies.

In addition to Spitzer and WIYN, Rines and his team used a telescope formerly known as the Multiple Mirror Telescope and now called MMT near Tucson, Ariz., to confirm that the four galaxies are intertwined, and NASA's Chandra X-ray Observatory to weigh the mass of the giant cluster of galaxies in which the merger was discovered. Both Spitzer and WIYN, also near Tucson, Ariz., were used to study the plume.

Other authors of this paper include Rose Finn of Siena College, Loudonville, N.Y.; and Alexey Vikhlinin of the Harvard-Smithsonian Center for Astrophysics.

Astronomers have discovered a chaotic scene unlike any witnessed before in a cosmic "train wreck" between giant galaxy clusters. NASA's Chandra X-ray Observatory and optical telescopes revealed a dark matter core that was mostly devoid of galaxies, which may pose problems for current theories of dark matter behavior.

"These results challenge our understanding of the way clusters merge," said Dr. Andisheh Mahdavi of the University of Victoria, British Columbia. "Or, they possibly make us even reexamine the nature of dark matter itself."

darkmatter.jpg (34.5 kB . 398x398 - viewed 6226 times)This multi-wavelength image of Abell 520 shows the aftermath of a complicated collision of galaxy clusters, some of the most massive objects in the Universe. In this image, the hot gas as detected by Chandra is colored red. Optical data from the Canada-France-Hawaii and Subaru telescopes shows the starlight from the individual galaxies (yellow and orange). The location of most of the matter in thecluster (blue) was also found using these telescopes, by tracing the subtle light-bending effects on distant galaxies. This material is dominated by dark matter. Credit: X-ray: NASA/CXC/UVic./A.Mahdavi et al. Optical/Lensing: CFHT/UVic./A.Mahdavi et

There are three main components to galaxy clusters: individual galaxies composed of billions of stars, hot gas in between the galaxies, and dark matter, a mysterious substance that dominates the cluster mass and can be detected only through its gravitational effects.

Optical telescopes can observe the starlight from the individual galaxies, and can infer the location of dark matter by its subtle light-bending effects on distant galaxies. X-ray telescopes like Chandra detect the multimillion-degree gas.

A popular theory of dark matter predicts that dark matter and galaxies should stay together, even during a violent collision, as observed in the case of the so-called Bullet Cluster. However, when the Chandra data of the galaxy cluster system known as Abell 520 was mapped along with the optical data from the Canada-France-Hawaii Telescope and Subaru Telescope atop Mauna Kea, HI, a puzzling picture emerged. A dark matter core was found, which also contained hot gas but no bright galaxies.

"It blew us away that it looks like the galaxies are removed from the densest core of dark matter," said Dr. Hendrik Hoekstra, also of University of Victoria. "This would be the first time we've seen such a thing and could be a huge test of our knowledge of how dark matter behaves."

In addition to the dark matter core, a corresponding "light region" containing a group of galaxies with little or no dark matter was also detected. The dark matter appears to have separated from the galaxies.

"The observation of this group of galaxies that is almost devoid of dark matter flies in the face of our current understanding of the cosmos," said Dr. Arif Babul, University of Victoria. "Our standard model is that a bound group of galaxies like this should have a lot of dark matter. What does it mean that this one doesn't?"

In the Bullet Cluster, known as 1E 0657-56, the hot gas is slowed down during the collision but the galaxies and dark matter appear to continue on unimpeded. In Abell 520, it appears that the galaxies were unimpeded by the collision, as expected, while a significant amount of dark matter has remained in the middle of the cluster along with the hot gas.

Mahdavi and his colleagues have two possible explanations for their findings, both of which are uncomfortable for prevailing theories. The first option is that the galaxies were separated from the dark matter through a complex set of gravitational "slingshots." This explanation is problematic because computer simulations have not been able to produce slingshots that are nearly powerful enough to cause such a separation.

The second option is that dark matter is affected not only by gravity, but also by an as-yet-unknown interaction between dark matter particles. This exciting alternative would require new physics and could be difficult to reconcile with observations of other galaxies and galaxy clusters, such as the aforementioned Bullet Cluster.

In order to confirm and fully untangle the evidence for the Abell 520 dark matter core, the researchers have secured time for new data from Chandra plus the Hubble Space Telescope. With the additional observations, the team hopes to resolve the mystery surrounding this system.

Questions remain unresolved as to whether the Neanderthals died out because of competition with modern people or because of deteriorating climatic conditions. Although scientists have gained increased knowledge of past climate it has been difficult to pinpoint the climatic character at the time of the Neanderthal disappearance. A new study by an international team of researchers, published this week in the prestigious journal Nature, has developed a breakthrough approach to address this issue (Nature, September 13, 2007).

"Our findings suggest that there was no single climatic event that caused the extinction of the Neanderthals" says palaeoanthro-pologist Katerina Harvati. Only a controversial date for very late Neanderthal survival places their disappearance just before a major environmental shift. "Even in this case" continues Harvati "the role of climate would have been indirect, perhaps promoting competition with other human groups".

"There are three main limitations to understanding the role of climate in the Neanderthal extinction" explains palaeoecologist Chronis Tzedakis: uncertainty over the exact timing of the Neanderthal disappearance; uncertainties in converting radiocarbon dates to actual calendar years; and the chronological imprecision of the ancient climate record. "Our novel method circumvents the last two problems" adds palaeoclimatologist Konrad Hughen. "We were therefore able to provide a much more accurate picture of the climatic background at the time of the Neanderthal disappearance". "More generally," continues Hughen "our approach offers the huge potential to unravel the role of climate in critical events of the recent fossil record as it can be applied to any radiocarbon date from any deposit".

The new method was applied by the researchers to three possible dates for the Neanderthal extinction obtained from Gorham’s cave, Gibraltar - a site thought to have been occupied by some of the latest surviving Neanderthals. The first two of these dates (~32 and ~28 thousand radiocarbon years ago) relate to conditions that are not distinct from the general climatic instability of the last glacial period. The much more controversial date of ~24 thousand radiocarbon years ago places the last Neanderthals just before a major environmental shift, with an expansion of ice sheets and onset of cold conditions in northern Europe. Gibraltar’s climate, however, remained relatively unaffected "perhaps as a result of warm water from the subtropical Atlantic entering the western Mediterranean" according to palaeoceanographer Isabel Cacho.

Thermal images of planet Neptune taken with VISIR on ESO's Very Large Telescope, obtained on 1 and 2 September 2006. These thermal images show a 'hot' south pole on Neptune. These warmer temperatures provide an avenue for methane to escape out of the deep atmosphere. Scientists say Neptune's south pole is 'hotter' than anywhere else on the planet by about 10 degrees Celsius. The average temperature on Neptune is about minus 200 degrees Celsius. The upper left image samples temperatures near the top of Neptune's troposphere (near 100 mbar pressure). The hottest temperatures are located at the lower part of the image at Neptune's south pole (see the graphic at the upper right). The lower two images, taken 6.3 hours apart, sample temperatures at higher altitudes in Neptune's stratosphere. They do show generally warmer temperatures near, but not at, the south pole. In addition they show a warm area which can be seen in the lower left image and rotated completely around the planet in the lower right image.

Super stuff in here. Thanks to this thread, I now have a pletora of new screen wallpapers.Planets with four parents? C[8D] [8D]L

Mom - where's that? Is that real?Perhaps honey, perhaps..... []

Now I know they're not exactly 'last weeks' and if they're a really old hat for ya then I'll happily bazook this post..... just yell!

Cell on the move Dr Aleksandar Ivetic, of Imperial College, London, won the British Heart Foundation picture of the year with this image of a migrating cell. The vivid colours come from the markers used to visualise the location of different cytoskeleton proteins essential for cell movement. ...sorry, you cannot view external links. To see them, please
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Mysterious microbubbleInjected preparations of tiny ‘microbubbles’ can be used to enhance the contrast and distinguish different structures within the body during ultrasound diagnosis of heart disease. This image by Raniska Tente, of the University of Edinburgh, is a computer-enhanced microscope image of a microbubble, just 100 millionths of a metre in diameter....sorry, you cannot view external links. To see them, please
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Heart muscle Heart muscle is made of different cell types that ‘talk’ to each other so the tissue can respond to changing conditions and efficiently pump blood round the body. This image by Patrizia Camelliti and Peter Kohl shows the microscopic architecture of heart muscle, showing the muscle in red closely associated with fibroblast cells in green. ...sorry, you cannot view external links. To see them, please
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Diseased blood vesselsDNA microarray technology allows scientists to quickly analyse the activity of thousands of genes in a single tissue sample. Here, Marianna Papaspyridonos and David Greaves from Oxford University, have tested gene activity in white blood cells from diseased blood vessels. Each spot represents a single gene – the brightest are the most active. ...sorry, you cannot view external links. To see them, please
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Cassini is on the trail of a runaway mysteryNASA/JPL NEWS RELEASEPosted: October 8, 2007

NASA scientists are on the trail of Iapetus' mysterious dark side, which seems to be home to a bizarre "runaway" process that is transporting vaporized water ice from the dark areas to the white areas of the Saturnian moon.

This "thermal segregation" model may explain many details of the moon's strange and dramatically two-toned appearance, which have been revealed exquisitely in images collected during a recent close flyby of Iapetus by NASA's Cassini spacecraft.

Infrared observations from the flyby confirm that the dark material is warm enough (approximately minus 230 degrees Fahrenheit or 127 Kelvin) for very slow release of water vapor from water ice, and this process is probably a major factor in determining the distinct brightness boundaries.

"The side of Iapetus that faces forward in its orbit around Saturn is being darkened by some mysterious process," said John Spencer, Cassini scientist with the composite infrared spectrometer team from the Southwest Research Institute, Boulder, Colo.

Using multiple instruments on Cassini, scientists are piecing together a complex story to explain the bright and dark faces of Iapetus. But yet to be fully understood is where the dark material is coming from. Is it native or from outside the moon? It has long been hypothesized that this material did not originate from within Iapetus, but instead was derived from other moons orbiting at a much greater distance from Saturn in a direction opposite to Iapetus.

Scientists are now converging on the notion that the darkening process in fact began in this manner, and that thermal effects subsequently enhanced the contrast to what we see today.

"It's interesting to ponder that a more than 30-year-old idea might still help explain the brightness difference on Iapetus," said Tilmann Denk, Cassini imaging scientist at the Free University in Berlin, Germany. "Dusty material spiraling in from outer moons hits Iapetus head-on, and causes the forward-facing side of Iapetus to look different than the rest of the moon."

Once the leading side is even slightly dark, thermal segregation can proceed rapidly. A dark surface will absorb more sunlight and warm up, explains Spencer, so the water ice on the surface evaporates. The water vapor then condenses on the nearest cold spot, which could be Iapetus's poles, and possibly bright, icy areas at lower latitudes on the side of the moon facing in the opposite direction of its orbit. So the dark stuff loses its surface ice and gets darker, and the bright stuff accumulates ice and gets brighter, in a runaway process.

Scientists say the result is that there are virtually no shades of gray on Iapetus. There is only white and very dark.

Ultraviolet data also show a non-ice component in the bright, white regions of Iapetus. Spectroscopic analysis will reveal whether the composition of the material on the dark hemisphere is the same as the dark material that is present within the bright terrain.

"The ultraviolet data tell us a lot about where the water ice is and where the non-water ice stuff is. At first glance, the two populations do not appear to be present in the pattern we expected, which is very interesting," said Amanda Hendrix, Cassini scientist on the ultraviolet imaging spectrograph team at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

Because of the presence of very small craters that excavate the bright ice beneath, scientists also believe that the dark material is thin, a result consistent with previous Cassini radar results. But some local areas may be thicker. The dark material seems to lie on top of the bright region, consistent with the idea that it is a residual left behind by the sublimated water ice.

Some other mysteries are coming together. There are more data on the signature mountain ridge that gives Iapetus its "walnut" appearance. In some places it appears subdued. One big question that remains is why it does not go all the way around.

Was it partially destroyed after it formed, or did it never extend all the way around the moon? Scientists have ruled out that it is a youthful feature because it is pitted with craters, indicating it is old. And the ridge looks too solid and competent to be the result of an equatorial ring around the moon collapsing onto its surface. The ring theory cannot explain features that look like tectonic structures in the new high resolution images.

Over the next few months, scientists hope to learn more about Iapetus' mysteries.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the Cassini mission for NASA's Science Mission Directorate, Washington, D.C.

BOULDER—In a landmark test flight, the National Center for Atmospheric Research (NCAR) and a team of research partners this month successfully launched a solar telescope to an altitude of 120,000 feet, borne by a balloon larger than a Boeing 747 jumbo jet. The test clears the way for long-duration polar balloon flights beginning in 2009 that will capture unprecedented details of the Sun's surface.

"This unique research project will enable us to view features of the Sun that we've never seen before," says Michael Knölker, director of NCAR's High Altitude Observatory and a principal investigator on the project. "We hope to unlock important mysteries about the Sun's magnetic field structures, which at times can cause electromagnetic storms in our upper atmosphere and may have an impact on Earth's climate."

The project, known as Sunrise, is an international collaboration involving NCAR, NASA, Germany's Max Planck Institute for Solar System Research and Kiepenheuer Institute for Solar Physics, Spain's Astrophysics Institute of the Canary Islands, and the Swedish Space Corporation. Additional U.S. partners include the Lockheed Martin Corporation and the University of Chicago. Funding for NCAR's work on the project comes from NASA and from the National Science Foundation, which is NCAR's primary sponsor.

The project may usher in a new generation of balloon-borne scientific missions that cost less than sending instruments into space. Scientists also can test an instrument on a balloon before making a commitment to launch it on a rocket.

The balloon, with its gondola of scientific instruments, was launched successfully on the morning of October 3 from the Columbia Scientific Balloon Facility in Fort Sumner, New Mexico. It flew for about 10 hours, capturing stable images of the solar surface and additional data from the various instruments of the sophisticated payload. The gondola then separated from the balloon and descended with a parachute, landing safely in a field outside Dalhart, Texas.

"We were able to verify the workings of the entire system end to end," says David Elmore, an NCAR engineer who oversaw the test flight. "We can now move on to planning the first full-scale mission with confidence."Observing the midnight Sun

The ultimate goal of the Sunrise project is to investigate the structure and dynamics of the Sun's magnetic fields. The fields fuel solar activity, including plasma storms that buffet Earth's outer atmosphere and affect sensitive telecommunications and power systems. The fields also cause variations in solar radiation, which may be significant factors in long-term changes in Earth's climate.

The Sunrise project is scheduled next for a multiday flight over the Arctic in the summer of 2009, launching from Kiruna, Sweden. By taking advantage of the midnight Sun, the telescope will be able to capture continuous images for a period of several days to as long as two weeks, possibly orbiting the Arctic. It may be launched later on another long-distance flight over the Arctic or the Antarctic.

At an altitude of 120,000 feet, the telescope will rise above most of the turbulence of the atmosphere and ultraviolet-absorbing water vapor and ozone. It will be able to view stable images in the ultraviolet range, which allow for higher resolution than can be obtained from Earth's surface.

The telescope will capture features on the solar surface as small as 30 kilometers across (about 19 miles), more than double the resolution achieved by any other instrument to date. This will enable scientists to examine structures on the Sun that are believed to be key to understanding the mechanisms driving solar activity. In addition, by observing the same area during an entire flight over high latitudes in summer, the telescope will enable scientists to continually witness changes in the magnetic fields without the interruption of night.

The Sunrise project has presented engineers with a number of extraordinary challenges. The balloon is designed to carry 6,000 pounds of equipment, including a 1-meter (39-inch) solar telescope, additional observing instruments, communications equipment, computers and disk drives, solar panels, and roll cages and crush pads to protect the payload on landing. The equipment must be able to withstand dramatic changes in temperature, and the steel and aluminum gondola cannot vibrate in ways that could interfere with the operation of the telescope.

One of the most difficult aspects of the engineering work was to design the gondola in such a way that the telescope in flight would remain focused on a specific and relatively tiny area of the Sun, even while twisting on a soaring balloon for a week or longer during the full-scale research missions. To accomplish this, the gondola includes both a torque motor drive to keep the gondola and telescope in the correct orientation and a precision guiding and compensation system to constantly correct the telescope's aim.

In addition to the telescope, the gondola on its full-scale research missions will carry a polarimetric spectrograph that will measure wavelengths in the Sun's electromagnetic spectrum and enable scientists to make inferences about its magnetic fields. Another instrument, known as an imaging magnetograph, will provide two-dimensional magnetic field maps.

Because the gondola is designed to withstand considerable force when it lands, the instruments can be launched on repeated missions.

"This is a very economical way of rising above the atmosphere and capturing images that cannot be captured from Earth," Knölker says. "What we are doing is laying the groundwork for the next generation of space flights."

SOURCE: The University Corporation For Atmospheric Research...sorry, you cannot view external links. To see them, please
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During his visit to ESO's Very Large Telescope at Paranal, the European Commissioner for Science and Research, Janez Potočnik, participated in an observing sequence and took images of a beautiful spiral galaxy.

The visit took place on 27 October and the Commissioner observed with one of the FORS instruments on Antu, the first 8.2-m Unit Telescope of the VLT.

"Two hours bus ride from the nearest town, Antofagasta, in the middle of nowhere and at 2 600 m altitude, rises a state of the art astronomical observatory at which scientists from across Europe venture to exploit some of the most advanced technologies and sophisticated techniques available within astronomy. One of the facilities is the VLT, the Very Large Telescope, with which, together with the other telescopes, scientists can study objects at the far edge of the Universe," wrote Potočnik on his blog.

Known until now as a simple number in a catalogue, NGC 134, the 'Island in the Universe' that was observed by the Commissioner is replete with remarkable attributes, and the VLT has clapped its eyes on them. Just like our own Galaxy, NGC 134 is a barred spiral with its spiral arms loosely wrapped around a bright, bar-shaped central region.

One feature that stands out is its warped disc. While a galaxy's disc is often pictured as a flat structure of gas and stars surrounding the galaxy's centre, a warped disc is a structure that, when viewed sideways, resembles a bent record album left out too long in the burning Sun.

Warps are actually not atypical. More than half of the spiral galaxies do show warps one way or another, and our own Milky Way also has a small warp.

Many theories exist to explain warps. One possibility is that warps are the aftermath of interactions or collisions between galaxies. These can also produce tails of material being pulled out from the galaxy. The VLT image reveals that NGC 134 also appears to have a tail of gas stripped from the top edge of the disc.

So did NGC 134 have a striking encounter with another galaxy in the past? Or is some other galaxy out there exerting a gravitational pull on it? This is a riddle astronomers need to solve.

The superb VLT image also shows that the galaxy has its fair share of ionised hydrogen regions (HII regions) lounging along its spiral arms. Seen in the image as red features, these are glowing clouds of hot gas in which stars are forming. The galaxy also shows prominent dark lanes of dust across the disc, obscuring part of the galaxy's starlight.

Studying galaxies like NGC 134 is an excellent way to learn more about our own Galaxy.

NGC 134 was discovered by Sir John Herschel at the Cape of Good Hope and is located in the Sculptor southern constellation. The galaxy is located about 60 million light-years away - when the light that was captured by the VLT originally left the galaxy, a dramatic episode of mass extinction had led to the disappearance of dinosaurs on Earth, paving the way for the appearance of mammals and later specifically of humans, who have built unique high-tech installations in the Atacama desert to satisfy their curiosity about the workings of the Universe. Still, NGC 134 is not very far away, by cosmological standards. It is the dominant member of a small group of galaxies that belongs to the Virgo or Local Supercluster and is one of the 200 brightest galaxies in our skies.

Neil likes the really biiiiiiiiiiiiig things - I get just as much kick out of the really tiiiiiiiiiiiny things

minature wonders []

Porpita porpita, Blue button (jellyfish relative) - not one organism but many joined at the gas-filled hub that keeps the colony afloat. Each tentacle has a specialized role in the cooperative: catching prey, digesting or reproducing. The pigment blocks UV rays....sorry, you cannot view external links. To see them, please
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Clio pyramidata is a pteropod - a swimming snail - with a shell made out of aragon and was one of the first zooplankton species ever to have its genes sequenced at sea.

Baby octopus

Another jelly - Small planktonic jellyfish with bright green-fluorescent tentacles. The red fluorescence in the middle of the jellyfish comes from chlorophyll in the ingested algae. Image curtesy of Mikhail Matz.

A new image from NASA's Spitzer Space Telescope shows a baby star 1,140 light-years away from Earth blowing two massive "bubbles." But instead of bubble gum, this youngster, called HH 46/47, is using powerful jets of gas to make bubbles in outer space.

The infant star can be seen as a white spot toward the center of the Spitzer image. The two bubbles are shown as hollow elliptical shells of bluish-green material extending from the star. Wisps of green in the image reveal warm molecular hydrogen gas, while the bluish tints are from starlight scattered by surrounding dust.

These bubbles formed when powerful jets of gas, traveling at 200 to 300 kilometers per second, or about 120 to 190 miles per second, smashed into the cosmic cloud of gas and dust that surrounds HH 46/47. Red specks at the end of each bubble show the presence of hot sulfur and iron gas where the star's narrow jets are currently crashing head-on into the cosmic cloud's gas and dust material.

According to Thangasamy Velusamy of NASA's Jet Propulsion Laboratory in Pasadena, Calif., baby stars and their potential planet-forming disks grow by gravitationally pulling in and absorbing surrounding gas and dust. Scientists suspect that these disks stop growing when the central baby star develops powerful winds and jets that blow away surrounding material.

"Spitzer can image these jets and winds in infrared light and help us understand the details of these phenomena," says Velusamy.

For astronomers who know what to look for, Spitzer's supersensitive infrared instruments are excellent tools for studying young stars embedded within thick clouds of cosmic dust and gas, revealing information about their growth. However, Velusamy notes that it is often difficult for most people to get a clear, detailed picture of infant stars and their "growing pains."

"When you see a star through a telescope, its image is blurred in a known way, and the smaller the telescope the larger is the blurring," he says.

To clear up this blurring, astronomers at JPL developed an advanced image-processing technique for Spitzer data called Hi-Res deconvolution. This process reduces blurring and makes the image sharper and cleaner, enabling astronomers to see the emissions around forming stars in greater detail. When Velusamy and his team applied this technique to the Spitzer image of HH 46/47, they were able to see winds from the star and jets of gas that are carving the celestial bubbles.

According to William Langer, also of JPL, this image will help scientists determine which of many different mechanisms are responsible for producing the winds and jets of baby stars.

This infrared image is a three-color composite, with data at 3.6 microns represented in blue, 4.5 and 5.8 microns shown in green, and 24 microns represented as red.

This paper on HH46/47 by Velusamy, Langer, and Kenneth Marsh, all of JPL, was published in the October issue of Astrophysical Journal Letters.

Imseweage1.jpg (28.72 kB . 557x549 - viewed 5150 times)This is a composite of four images combined to show the illuminated crescent of Earth and the cities of the northern hemisphere. The images were acquired with the OSIRIS Wide Angle Camera (WAC) during Rosetta’s second Earth swing-by on 13 November.

This image showing islands of light created by human habitation was taken with the OSIRIS WAC at 19:45 CET, about 2 hours before the closest approach of the spacecraft to Earth. At the time, Rosetta was about 80 000 km above the Indian Ocean where the local time approached midnight (the angle between Sun, Earth and Rosetta was about 160°). The image was taken with a five-second exposure of the WAC with the red filter.

This image showing Earth’s illuminated crescent was taken with the WAC at 20:05 CET as Rosetta was about 75 000 km from Earth. The crescent seen is around Antarctica. The image is a colour composite combining images obtained at various wavelengths.

-MaunderCrater_H1.jpg (118.62 kB . 500x400 - viewed 4288 times)/b] The above image shows the striking Maunder crater located in the region of Noachis Terra on Mars. The crater lies at 50° South and 2° East. The High Resolution Stereo Camera (HRSC) on ESA’s Mars Express orbiter took pictures of the Noachis Terra region during orbits 2412 and 2467 on 29 November and 14 December 2005 respectively, with a ground resolution of approximately 15 metres per pixel.

Named after the british astronomer Edward W. Maunder, the crater located halfway between Argyre Planitia and Hellas Planitia on the southern Highlands of Mars.

This perspective view has been calculated from the digital terrain model derived from the HRSC stereo channels.

Jupiter’s moon Europa is just as far away as ever, but new research is bringing scientists closer to being able to explore its tantalizing ice-covered ocean and determine its potential for harboring life.

“We’ve learned a lot about Europa in the past few years,” says William McKinnon, professor of Earth and Planetary Sciences at Washington University in St. Louis, Mo.

“Before we were almost sure that there was an ocean, but now the scientific community has come to a consensus that there most certainly is an ocean. We’re ready to take the next step and explore that ocean and the ice shell that overlays it. We have a number of new discoveries and techniques that can help us do that.”

McKinnon is discussing some of these recent findings and new opportunities for exploring Europa in a news briefing today at the meeting of the American Geophysical Union in San Francisco. He is joined by colleagues Donald Blankenship, research scientist at the Institute for Geophysics at the University of Texas at Austin’s Jackson School of Geosciences., and Peter Doran, associate professor of Earth and Environmental Sciences, University of Illinois at Chicago.

McKinnon points to refined methods that can use combined measurements of gravity and the magnetic field made from orbit to characterize Europa's ocean. By observing how the moon flexes and deforms and by measuring magnetic variations, researchers can determine how thick or thin the ice is over the ocean and even learn how salty the ocean is. A new model shows that radiation on Europa is much less, up to two-thirds less, than previous models predicted, making the environment much more hospitable for orbiting spacecraft or landers to operate.

Sophisticated reprocessing of data from the Galileo mission has revealed new information about the chemistry of Europa’s surface. It maps the presence of carbon dioxide, an important chemical for life, most probably coming from the ocean beneath the surface. This indicates that improved measurements from orbit have the chance to detect compounds not found in the Galileo data.

Future explorations of Europa will benefit from lessons learned from the Cassini spacecraft’s recent findings of active geysers on Saturn’s moon Enceladus. “Europa is a young, geologically active body like Enceladus,” says McKinnon. Galileo didn’t see any plumes on Europa like those spouting from Enceladus, but it didn’t have the best instrumentation to detect the telltale hot spots. “Now we know what we should look for,” says McKinnon, “and we should expect the unexpected.”

Thin.Thick.Shell.jpg (87.26 kB . 758x375 - viewed 4503 times)olor=blue]Thick or thin ice shell on Jupiter’s moon Europa? Scientists are all but certain thatEuropa has an ocean underneath its surface ice, but do not know how thick this ice might be. This artists’ conception illustrates two possible cut-away views through Europa’s ice shell. In both heat escapes, possibly volcanically, from Europa’s rocky mantle and is carried upward by buoyant oceanic currents. If the heat from below is intense and the ice shell is thin enough (left), the ice shell can directly melt, causing what are called “chaos” on Europa, regions of what appear to be broken, rotated, and tilted ice blocks. On the other hand, if the ice shell is sufficiently thick (right), the less intense interior heat will be transferred to the warmer ice at the bottom of the shell, and additional heat is generated by tidal squeezing of the warmer ice. This warmer ice will slowly rise, flowing as glaciers do on Earth, and the slow but steady motion may also disrupt the extremely cold, brittle ice at the surface. Europa is no larger than Earth’s moon, and its internal heating stems from its eccentric orbit about Jupiter, seen in the distance. As tides raised by Jupiter in Europa’s ocean rise and fall, they may cause cracking, additional heating, and even venting of water vapor into the airless sky above Europa’s icy surface. (Artwork by Michael Carroll.) Credit: NASA/JPL.[/color][/b][/size]

New radar sounding techniques will be a key component for exploring Europa. “There have been theories about whether the ice above the ocean is thick or thin, and now we have the ability to determine this with radar,” says Blankenship. “That’s been proved by the radar on Mars Express, which imaged the north polar cap of Mars, and the higher-resolution radar on the Mars Reconnaissance Orbiter. Radar can give us a detailed cross section through the ice shell on Europa.” The ice-penetrating radar will also be able to locate liquid water both within and beneath the shell, he continues, just as it can spot water within crevasses and lakes beneath the ice of Antarctica. "Free water within the icy shell and its relationship to the underlying ocean will be a critical factor in determining the habitability of Europa."

Byrd Glacier, Antarctica. Analogs in Antarctica's ice-covered lakes will provide critical testing grounds for the technology needed to explore Europa's ice-covered ocean. More info>>Researchers are also preparing for the day in the future when they will be able to get to Europa's surface and ultimately into its ocean to explore it directly. "In the meantime, we're using extreme environments on Earth as our laboratory," says Doran. "Ice-covered lakes in Antarctica are good, small-scale analogs to what we might find on Europa." Doran is lead investigator of a project called Endurance, which, in collaboration with Stone Aerospace, is developing an autonomous underwater robotic vehicle, to test approaches and procedures for exploring Europa's ocean. The project is funded by NASA's Astrobiology Science and Technology for Exploring Planets program.

"We're testing the vehicle in Wisconsin in February 2008," Doran says, "and then we'll be deploying it in Antarctica later in the year." The robotic explorer will be able to create three-dimensional maps of the subsurface Antarctic lake. It will also be able to map the biochemistry of the water body, pinpointing the chemical signatures that may indicate life.

For Europa, under-ice exploration lies in the distant future. In the meantime, say the researchers, a closer look at Europa is possible from an orbiting spacecraft able to measure gravity and magnetic fields, determine surface composition, search for active or recent eruptions, and use radar to understand the relationship between the surface and the sub-surface.

SOURCE: JACKSON SCHOOL OF GEOSCIENCES...sorry, you cannot view external links. To see them, please
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WASHINGTON - A powerful jet from a super massive black hole is blasting a nearby galaxy, according to new findings from NASA observatories. This never-before witnessed galactic violence may have a profound effect on planets in the jet's path and trigger a burst of star formation in its destructive wake.

blackhole.jpg (9.73 kB . 398x290 - viewed 3725 times)This composite image shows the jet from a black hole at the center of a galaxy striking the edge of another galaxy, the first time such an interaction has been found. X-rays from Chandra (colored purple), optical and ultraviolet (UV) data from Hubble (red and orange), and radio emission from the Very Large Array (VLA) and MERLIN (blue) show how the jet from the main galaxy on the lower left is striking its companion galaxy to the upper right.

Known as 3C321, the system contains two galaxies in orbit around each other. Data from NASA's Chandra X-ray Observatory show both galaxies contain super massive black holes at their centers, but the larger galaxy has a jet emanating from the vicinity of its black hole. The smaller galaxy apparently has swung into the path of this jet.

This "death star" galaxy was discovered through the combined efforts of both space and ground-based telescopes. NASA's Chandra X-ray Observatory, Hubble Space Telescope, and Spitzer Space Telescope were part of the effort. The Very Large Array telescope, Socorro, N.M., and the Multi-Element Radio Linked Interferometer Network (MERLIN) telescopes in the United Kingdom also were needed for the finding.

"We've seen many jets produced by black holes, but this is the first time we've seen one punch into another galaxy like we're seeing here," said Dan Evans, a scientist at the Harvard-Smithsonian Center for Astrophysics and leader of the study. "This jet could be causing all sorts of problems for the smaller galaxy it is pummeling."

Jets from super massive black holes produce high amounts of radiation, especially high-energy X-rays and gamma-rays, which can be lethal in large quantities. The combined effects of this radiation and particles traveling at almost the speed of light could severely damage the atmospheres of planets lying in the path of the jet. For example, protective layers of ozone in the upper atmosphere of planets could be destroyed.

blackholeart.jpg (24.46 kB . 398x290 - viewed 3891 times)An artist's illustration of the system, showing the main galaxy and the companion galaxy. A jet of particles generated by a supermassive black hole at the center of the main galaxy is striking the companion galaxy. The jet is disrupted and deflected by this impact. The key features of this system are labeled in the final view.

Credit: NASA/CXC/M. Weiss

Jets produced by super massive black holes transport enormous amounts of energy far from black holes and enable them to affect matter on scales vastly larger than the size of the black hole. Learning more about jets is a key goal for astrophysical research.

"We see jets all over the universe, but we're still struggling to understand some of their basic properties," said co-investigator Martin Hardcastle of the University of Hertfordshire in the United Kingdom. "This system of 3C321 gives us a chance to learn how they're affected when they slam into something like a galaxy and what they do after that."

The effect of the jet on the companion galaxy is likely to be substantial, because the galaxies in 3C321 are extremely close at a distance of only about 20,000 light years apart. They lie approximately the same distance as Earth is from the center of the Milky Way galaxy.

A bright spot in the Very Large Array and MERLIN images shows where the jet has struck the side of the galaxy, dissipating some of the jet's energy. The collision disrupted and deflected the jet.

Another unique aspect of the discovery in 3C321 is how relatively short-lived this event is on a cosmic time scale. Features seen in the Very Large Array and Chandra images indicate that the jet began impacting the galaxy about one million years ago, a small fraction of the system's lifetime. This means such an alignment is quite rare in the nearby universe, making 3C321 an important opportunity to study such a phenomenon.

It is possible the event is not all bad news for the galaxy being struck by the jet. The massive influx of energy and radiation from the jet could induce the formation of large numbers of stars and planets after its initial wake of destruction is complete.

The results from Evans and his colleagues will appear in The Astrophysical Journal. NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the agency's Science Mission Directorate. The Smithsonian Astrophysical Observatory controls science and flight operations from the Chandra X-ray Center in Cambridge, Mass.

farside_apollo16_big.jpg (112.36 kB . 590x605 - viewed 5313 times)e far side of the Moon is the lunar hemisphere that is permanently turned away from the Earth. The far hemisphere was first photographed by the Soviet Luna 3 probe in 1959, and was first directly observed by human eyes when the Apollo 8 mission orbited the Moon in 1968. The rugged terrain is distinguished by a multitude of crater impacts, as well as relatively few lunar maria. It includes the largest known impact feature in the Solar System: the South Pole-Aitken basin. The far side has been suggested as a potential location for a large radio telescope, as it would be shielded from possible radio interference from Earth

Sunspot is harbinger of the new solar cycleNOAA NEWS RELEASEPosted: January 7, 2008

A new 11-year cycle of heightened solar activity, bringing with it increased risks for power grids, critical military, civilian and airline communications, GPS signals and even cell phones and ATM transactions, showed signs it was on its way last week when the cycle's first sunspot appeared in the sun's Northern Hemisphere, NOAA scientists said.

"This sunspot is like the first robin of spring," said solar physicist Douglas Biesecker of NOAA's Space Weather Prediction Center. "In this case, it's an early omen of solar storms that will gradually increase over the next few years."

A sunspot is an area of highly organized magnetic activity on the surface of the sun. The new 11-year cycle, called Solar Cycle 24, is expected to build gradually, with the number of sunspots and solar storms reaching a maximum by 2011 or 2012, though devastating storms can occur at any time.

During a solar storm, highly charged material ejected from the sun may head toward Earth, where it can bring down power grids, disrupt critical communications, and threaten astronauts with harmful radiation. Storms can also knock out commercial communications satellites and swamp Global Positioning System signals. Routine activities such as talking on a cell phone or getting money from an ATM machine could suddenly halt over a large part of the globe.

"Our growing dependence on highly sophisticated, space-based technologies means we are far more vulnerable to space weather today than in the past," said Vice Admiral Conrad C. Lautenbacher, Jr., under secretary of commerce for oceans and atmosphere and NOAA administrator. "NOAA's space weather monitoring and forecasts are critical for the nation's ability to function smoothly during solar disturbances."

Last April, in coordination with an international panel of solar experts, NOAA issued a forecast that Solar Cycle 24 would start in March 2008, plus or minus six months. The panel was evenly split between those predicting a strong or weak cycle. Both camps agree that the sooner the new cycle takes over the waning previous cycle, the more likely that it will be a strong season with many sunspots and major storms, said Biesecker. Many more sunspots with Solar Cycle 24 traits must emerge before scientists consider the new cycle dominant, with the potential for more frequent storms.

The new sunspot, identified as #10,981, is the latest visible spot to appear since NOAA began numbering them on January 5, 1972. Its high-latitude location at 27 degrees North, and its negative polarity leading to the right in the Northern Hemisphere are clear-cut signs of a new solar cycle, according to NOAA experts. The first active regions and sunspots of a new solar cycle can emerge at high latitudes while those from the previous cycle continue to form closer to the equator.

SWPC is the nation's first alert for solar activity and its affects on Earth. The center's space weather forecasters issue outlooks for the next 11-year solar "season" and warn of individual storms occurring on the sun that could impact Earth. SWPC is one of NOAA's nine National Centers for Environmental Prediction and is also the warning agency of the International Space Environment Service (ISES), a consortium of 11 member nations.

NOAA is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and information service delivery for transportation, and by providing environmental stewardship of our nation's coastal and marine resources. Through the emerging Global Earth Observation System of Systems (GEOSS), NOAA is working with its federal partners, more than 70 countries and the European Commission to develop a global monitoring network that is as integrated as the planet it observes, predicts and protects

Hot cyclones churn at both ends of SaturnNASA/JPL NEWS RELEASEPosted: January 5, 2008

Despite more than a decade of winter darkness, Saturn's north pole is home to an unexpected hot spot remarkably similar to one at the planet's sunny south pole. The source of its heat is a mystery. Now, the first detailed views of the gas giant's high latitudes from the Cassini spacecraft reveal a matched set of hot cyclonic vortices, one at each pole.

While scientists already knew about the hot spot at Saturn's south pole from previous observations by the W. M. Keck Observatory in Hawaii, the north pole vortex was a surprise. The researchers report their findings in the Jan. 4 issue of Science.

"We had speculated that the south pole hot spot was connected to the southern, sunlit conditions," said Glenn Orton, a senior research scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif., and co-investigator on Cassini's composite infrared spectrometer. "Since the north pole has been deprived of sunlight since the arrival of winter in 1995, we didn't expect to find a similar feature there."

The infrared data show that the shadowed north pole vortex shares much the same structure and temperature as the one at the sunny south pole. The cores of both show a depletion of phospine gas, an imbalance probably caused by air moving downward into the lowest part of Saturn's atmosphere, the troposphere. Both polar vortices appear to be long-lasting and intrinsic parts of Saturn and are not related to the amount of sunlight received by one pole or the other.

"The hot spots are the result of air moving polewards, being compressed and heated up as it descends over the poles into the depths of Saturn," said Leigh Fletcher, a planetary scientist from the University of Oxford, England, and the lead author of the Science paper. "The driving forces behind the motion, and indeed the global motion of Saturn's atmosphere, still need to be understood."

Though similar, the two polar regions differ in one striking way. At the north pole, the newly discovered vortex is framed by the distinctive, long-lived and still unexplained polar hexagon. This mysterious feature encompassing the entire north pole was first spotted in the 1980s by NASA's Voyager 1 and 2 spacecraft. Cassini's infrared cameras also detected the hexagon in deep atmospheric clouds early in 2007.

In their paper, Fletcher and his colleagues report that the bright, warm hexagon is much higher than previous studies had shown. "It extends right to the top of the troposphere," says Fletcher. "It is associated with downward motion in the troposphere, though the cause of the hexagonal structure requires further study."

Winter lasts about 15 years on Saturn. Researchers anticipate that when the seasons change in the coming years and Saturn's north pole is once again in sunlight, they will be able to see a swirling vortex with high eye walls and dark central clouds like the one now visible at the south pole. "But Saturn may surprise us again," says Fletcher.

"The fact that Neptune shows a similar south polar hot spot whets our appetite for the strange dynamics of the poles of the other gas giants," Fletcher says.

More information about Jupiter's poles will come from NASA's Juno mission, currently scheduled for launch in 2011 and arrival in 2016.

Fletcher's research was funded by the United Kingdom's Science and Technology Facilities Council.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter was designed, developed and assembled at JPL. The science team for Cassini's composite infrared spectrometer team is based at NASA's Goddard Space Flight Center, Greenbelt, Md

Like people, galaxies come in different shapes and sizes. There are thin spirals both with and without central bulges of stars, and more rotund ellipticals that are themselves like giant bulges. Scientists have long held that all galaxies except the slender, bulgeless spirals harbor supermassive black holes at their cores. Furthermore, bulges were thought to be required for black holes to grow.

The new Spitzer observations throw this theory into question. The infrared telescope surveyed 32 flat and bulgeless galaxies and detected monstrous black holes lurking in the bellies of seven of them. The results imply that galaxy bulges are not necessary for black hole growth; instead, a mysterious invisible substance in galaxies called dark matter could play a role.

"This finding challenges the current paradigm. The fact that galaxies without bulges have black holes means that the bulges cannot be the determining factor, " said Shobita Satyapal of the George Mason University, Fairfax, Va. "It's possible that the dark matter that fills the halos around galaxies plays an important role in the early development of supermassive black holes."

Satyapal presented the findings at the 211th meeting of the American Astronomical Society in Austin, Texas. A study from Satyapal and her team will be published in the April 10 issue of the Astrophysical Journal.

Our own Milky Way is an example of a spiral galaxy with a bulge; from the side, it would look like a plane seen head-on, with its wings out to the side. Its black hole, though dormant and not actively "feeding," is several million times the mass of our sun.

Previous observations had suggested that bulges and black holes flourished together like symbiotic species. For instance, supermassive black holes are almost always about 0.2 percent the mass of their galaxies' bulges. In other words, the more massive the bulge, the more massive the black hole. Said Satyapal, "Scientists reasoned that somehow the formation and growth of galaxy bulges and their central black holes are intimately connected."

But a wrinkle appeared in this theory in 2003, when astronomers at the University of California, Berkeley, and Observatories of the Carnegie Institution of Washington, Pasadena, Calif., discovered a relatively "lightweight" supermassive black hole in a galaxy lacking a bulge. Then, earlier this year, Satyapal and her team uncovered a second supermassive black hole in a similarly svelte galaxy.

In the latest study, Satyapal and her colleagues report the discovery of six more hefty black holes in thin galaxies with minimal bulges, further weakening the "bulge-black hole" theory. Why hadn't anybody seen these black holes before? According to the scientists, bulgeless galaxies tend to be very dusty, letting little visible light escape. But infrared light can penetrate dust, so the team was able to use Spitzer's infrared spectrograph to reveal the "fingerprints" of active black holes lurking in galaxies millions of light years away.

"A feeding black hole spits out high-energy light that ionizes much of the gas in the core of the galaxy," said Satyapal. "In this case, Spitzer identified the unique fingerprint of highly ionized neon -- only a feeding black hole has the energy needed to excite neon to this state." The precise masses of the newfound black holes are unknown.

If bulges aren't necessary ingredients for baking up supermassive black holes, then perhaps dark matter is. Dark matter is the enigmatic substance that permeates galaxies and their surrounding halos, accounting for up to 90 percent of a galaxy's mass. So-called normal matter makes up stars, planets, living creatures and everything we see around us, whereas dark matter can't be seen. Only its gravitational effects can be felt. According to Satyapal, dark matter might somehow determine the mass of a black hole early on in the development of a galaxy.

"Maybe the bulge was just serving as a proxy for the dark matter mass -- the real determining factor behind the existence and mass of a black hole in a galaxy's center," said Satyapal.

Other authors of this study include: D. Vega of the George Mason University; R.P. Dudik of the George Mason University and NASA Goddard Space Flight Center, Greenbelt, Md.; N.P. Abel of the University of Cincinnati, Ohio; and Tim Heckman of the Johns Hopkins University, Baltimore, Md.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA. Spitzer's infrared spectrograph was built by Cornell University, Ithaca, N.Y. Its development was led by Jim Houck of Cornell.